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COSC1557: Introduction to Computing. Haibin Zhu, PhD. AssistProfessor Department of Computer Science Nipissing University (C) 2002. Instructor. Haibin Zhu, Ph. D. Assistant Professor, Department of CS and Math, Nipissing University Room: A124A Ext.: 4434 Email: haibinz@nipissingu.ca

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COSC1557: Introduction to Computing

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Cosc1557 introduction to computing l.jpg

COSC1557: Introduction to Computing

Haibin Zhu, PhD.

AssistProfessor

Department of Computer Science

Nipissing University

(C) 2002


Instructor l.jpg

Instructor

  • Haibin Zhu, Ph. D.

  • Assistant Professor, Department of CS and Math, Nipissing University

  • Room: A124A Ext.: 4434

  • Email: haibinz@nipissingu.ca

  • URL: http://www.nipissingu.ca/faculty/haibinz

  • Office Hour: Mon.–Fri. 2:30pm-4:30pm, and by appointment


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Nature and uses of the computer-, algorithms-, number systems, information representation; and organization, with an overview of computer hardware and software, computing systems and major applications. Ethical and societal issues arc discussed. An introduction to high-level languages with an emphasis on writing programs in C++.

Course Description


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Textbook and references

  • Textbook:Joel Adams and Larry Nyhoff, C++: An Introduction to Computing, 3/e. Prentice Hall, © 2003 ISBN: 0-13-091426-6

  • Lecture Notes on http://cs.calvin.edu/books/c++/intro/3e/PPSlides/

  • Student Supplements: CD-Lab Manual (ISBN: 013080648X)

  • Some Lab: http://cs.calvin.edu/books/c++/intro/3e/HandsOnC++/


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Beginning Snapshots

Chapter 0


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Objectives

  • Give an overview of computer science

    • Show its breadth

  • Provide context for computer science concepts

    • Events from the past

  • Describe basic components, organization of a computer


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Algorithms and Data Structures

Architecture

Artificial Intelligence and Robotics

Database and Information Retrieval

Human-Computer Communication

Numerical and Symbolic Computation

Operating Systems

Programming Languages

Software Methodology and Engineering

Social and Professional Context

Areas of Computer Science


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Important Concepts in Computer History

  • The mechanism of arithmetic

  • The stored program

  • The graphical user interface

  • The computer network


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First-Generation Computers

  • Vacuum tube computers1945-1956

    • ENIAC1943-1946

    • John Von Neumann's"First Draft of a Report onthe EDVAC"1945

    • First bug in a computer1945

    • UNIVAC1951


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Second Generation Computers

  • Used transistors1956-1963

  • FORTRAN1957

  • IBM 70901958

    LISP

  • COBOL1960

    ALGOL 60


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Third-Generation Computers

  • Chips and Integrated Circuits1964-1971

  • The IBM System/3601964

  • The PDP-81965

  • Douglas Englebart: the mouse, Two-D display, editing, hypermedia,1968

    Pascal

  • Ken Thompson: UNIX1969

    ARPANET – The beginning of the Internet


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Fourth-Generation Computers

  • Intel 4004 Chip1971

  • Dennis Richie: C1973

  • Ethernet

  • Court rules Atanasoff was legal inventor of first electronic digital computer

  • Altair, BASIC, Apple 11974

  • Apple II, Cray 1, Apple Corp.Microsoft Corp.1976

  • IBM PC1981


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Fourth-Generation Computers

  • Bjarne Stroustrup: C++1983

    Novell announces NetwareTCP/IP

  • Macintosh1984

  • Windows1985

  • Intel 386 Chip1986

  • Tim Berners—Lee: WWW1991

  • Linux1992


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Fourth-Generation Computers

  • Pentium chips, Power PC chip1993

    MOSAIC, Apple Newton

  • Netscape Navigator 1.0, Yahoo!1994Palm computing

  • James Gosling: JAVA1995Windows 95, Internet Explorer,Internet goes commercial

  • Windows 98, Apple's IMAC1998Microsoft's court case


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Fourth-Generation Computers

  • Y2K Problem, Powermac G41999

  • Windows 200020001 GHZ processors

  • Mac OS X2001Windows XP

  • Quantum Computer2002


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Graphical User Interface

  • Command line interface required precise and cryptic commands

  • Xerox PARK had developed GUI prototype in 1972

    • Steve Jobs saw it several years later and used new hardware capabilities to implement

  • GUI makes computer easy to use


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Network

  • Defn: Two or more computers connect to exchange resources

    • Processing power

    • Storage

    • Access to a printer

    • Software resources

    • Messages


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Network

  • Time sharing in early 1960s

    • Users communicate with host computer

  • ARPANET connected research center computers in 1969

    • Eventually developed into Internet

  • Local Area Network hardware and operating systems developed late 1970s

  • ISPs now affordable, widely available for even home computers


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Computer Organization

Hardware and Software

Calvin College


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Computing Systems

Computers have two kinds of components:

  • Hardware, consisting of its physical devices (CPU, memory, bus, storage devices, ...)

  • Software, consisting of the programs it has (Operating system, applications, utilities, ...)


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Hardware: CPU

Central Processing Unit (CPU):

  • the “brain” of the machine(?)

  • location of circuitry that performs arithmetic and logical ML statements

  • measurement: speed (roughly) in megahertz (millions of clock-ticks per second)

  • examples: Intel Pentium(PI, PII, PIII, P4), AMD K6, Motorola PowerPC, Sun SPARC,


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Hardware: RAM

Random Access Memory (RAM)

  • “main” memory, which is fast, but volatile...

  • analogous to a person’s short-term memory.

  • many tiny “on-off” switches: for convenience

    • “on” is represented by 1, “off” by 0.

  • each switch is called a binary digit, or bit.

    • 8 bits is called a byte.

    • 210 bytes =1024 bytes is called a kilobyte (1K)

    • 220 bytes is called a megabyte (1M).


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Hardware (Disk)

Secondary Memory (Disk):

  • Stable storage using magnetic or optical media.

  • Analogous to a person’s long-term memory.

  • Slower to access than RAM.

  • Examples:

    • floppy disk (measured in kilobytes)

    • hard disk (measured in gigabytes (230 bytes))

    • CD-ROM (measured in megabytes), ...


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Hardware: the Bus

The Bus:

  • Connects CPU to other hardware devices.

  • Analogous to a person’s spinal cord.

  • Speed measured in megahertz (like the CPU), but typically much slower than the CPU...

  • The bottleneck in most of today’s PCs.


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Hardware: Cache

While accessing RAM is faster than accessing secondary memory, it is still quite slow, relative to the rate at which the CPU runs.

To circumvent this problem, most systems add a fast cache memory to the CPU, to store recently used instructions and data.

(Assumption: Since such instructions/data were needed recently, they will be needed again in the near future.)


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CPU

Main

Memory

Secondary

Memory

cache

Bus

Hardware: Summary

Putting the pieces together:

Programs are stored (long-term) in secondary memory, and loaded into main memory to run, from which the CPU retrieves and executes their statements.


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Disk

CPU

RAM

Cache

OS

Bus

Software: OS

The operating system (OS) is loaded from secondary memory into main memory when the computer is turned on, and remains in memory until the computer is turned off.


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Software: OS

The OS acts as the “manager” of the system, making sure that each hardware device interacts smoothly with the others.

It also provides the interface by which the user interacts with the computer, and awaits user input if no application is running.

Examples: Windows 2000, Windows XP, Windows-NT, UNIX, Linux, Solaris, MacOS, ...


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Software: Applications

Applications are non-OS programs that perform some useful task, including word processors, spreadsheets, databases, web browsers, C++ compilers, ...

Example C++ compilers/environments:

  • CodeWarrior (MacOS, Win95, WinNT, Solaris)

  • GNU C++ (UNIX, Linux)

  • Turbo/Borland C++ (Win95, WinNT)

  • Visual C++ (Win95, WinNT)


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Software: User Programs

Programs that are neither OS programs nor applications are called user programs.

User programs are what you’ll be writing in this course.


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Disk

CPU

RAM

Cache

OS

App

Bus

Putting it all together

Programs and applications that are not running are stored on disk.


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Disk

CPU

RAM

Cache

OS

OS

App

App

Bus

Putting it all together

When you launch a program, the OS controls the CPU and loads the program from disk to RAM.


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Disk

CPU

RAM

Cache

OS

App

App

App

Bus

Putting it all together

The OS then relinquishes the CPU to the program, which begins to run.


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The Fetch-Execute Cycle

As the program runs, it repeatedly fetches the next instruction (from memory/cache), executes it, and stores any results back to memory.

Disk

CPU

RAM

Cache

OS

App

App

App

Bus

That’s all a computer does: fetch-execute-store, millions of times each second!


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Programming


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What is Programming?

A sequence of statements that instruct a computer in how to solve a problem is called a program.

The act of designing, writing and maintaining a program is called programming.

People who write programs are called programmers.


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What kinds of statementsdo computers understand?

A computer only understands machine language statements.

A machine language statement is a sequence of ones and zeros that cause the computer to perform a particular action, such as add, subtract, multiply, ...


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Machine Language (ML)

ML statements are stored in a computer’s memory, which is a sequence of switches.

For convenience of representation, an “on” switch is represented by 1, and an “off” switch is represented by 0.

ML thus appears to be binary (base-2):

0010111010110101


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Early Computers

... required a programmer to write in ML...

  • Easy to make mistakes!

  • Such mistakes are hard to find!

  • Not portable -- only runs on one kind of machine!

    Programming was very difficult!


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Assembler

ADD

0010111010110101

A Bright Idea

Devise a set of abbreviations (mnemonics) corresponding to the ML statements, plus a program to translate them into ML.

The abbreviations are an assembly language, and the program is called an assembler.


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Assembly Languages

Allowed a programmer to use mnemonics, which were more natural than binary.

  • Much easier to read programs

  • Much easier to find and fix mistakes

  • Still not portable to different machines


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High Level Languages

Devise a set of statements that are close to human language (if, while, do, ...), plus a program to translate them into ML.

The set of statements is called a high level language (HLL) and the program is called a compiler.


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1010110011110101

0000000000010000

0010111010110101

0000000000010010

0010111011111101

0000000000010100

Compiler

z = x + y;

HLL Compilers

Where an assembler translates one mnemonic into one ML statement, a HLL compiler translates one HLL statement into multiple ML statements.


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HLLs

High level languages (like C++) are

  • Much easier to read programs

  • Much easier to find and fix mistakes

  • Portable from one machine to another (so long as they keep to the language standard).


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Objectives in Programming

A program should solve a problem:

  • correctly (it actually solves the problem)

  • efficiently (without wasting time or space)

  • readably (understandable by another person)

  • in a user-friendly fashion (in a way that is easy for its user to use).


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Summary

A computer has two kinds of components:

  • Hardware: its CPU, RAM, Disk(s), ...

  • Software, its OS, Applications, and User Programs.

    There are “levels” to computer languages:

  • ML consists of “low” level binary statements, that is hard to read, write, and not portable.

  • Assembly uses “medium” level mnemonics: easier to read/write, but not portable.

  • C++ is a “high” level language that is even easier to read/write, and portable.


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