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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: [email protected]

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cosc1557 introduction to computing

COSC1557: Introduction to Computing

Haibin Zhu, PhD.

AssistProfessor

Department of Computer Science

Nipissing University

(C) 2002

instructor
Instructor
  • Haibin Zhu, Ph. D.
  • Assistant Professor, Department of CS and Math, Nipissing University
  • Room: A124A Ext.: 4434
  • Email: [email protected]
  • URL: http://www.nipissingu.ca/faculty/haibinz
  • Office Hour: Mon.–Fri. 2:30pm-4:30pm, and by appointment
course description
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
textbook and references
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++/
objectives
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
areas of computer science
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
important concepts in computer history
Important Concepts in Computer History
  • The mechanism of arithmetic
  • The stored program
  • The graphical user interface
  • The computer network
first generation computers
First-Generation Computers
  • Vacuum tube computers 1945-1956
    • ENIAC 1943-1946
    • John Von Neumann\'s"First Draft of a Report onthe EDVAC" 1945
    • First bug in a computer 1945
    • UNIVAC 1951
second generation computers
Second Generation Computers
  • Used transistors 1956-1963
  • FORTRAN 1957
  • IBM 7090 1958

LISP

  • COBOL 1960

ALGOL 60

third generation computers
Third-Generation Computers
  • Chips and Integrated Circuits 1964-1971
  • The IBM System/360 1964
  • The PDP-8 1965
  • Douglas Englebart: the mouse, Two-D display, editing, hypermedia, 1968

Pascal

  • Ken Thompson: UNIX 1969

ARPANET – The beginning of the Internet

fourth generation computers
Fourth-Generation Computers
  • Intel 4004 Chip 1971
  • Dennis Richie: C 1973
  • Ethernet
  • Court rules Atanasoff was legal inventor of first electronic digital computer
  • Altair, BASIC, Apple 1 1974
  • Apple II, Cray 1, Apple Corp.Microsoft Corp. 1976
  • IBM PC 1981
fourth generation computers13
Fourth-Generation Computers
  • Bjarne Stroustrup: C++ 1983

Novell announces NetwareTCP/IP

  • Macintosh 1984
  • Windows 1985
  • Intel 386 Chip 1986
  • Tim Berners—Lee: WWW 1991
  • Linux 1992
fourth generation computers14
Fourth-Generation Computers
  • Pentium chips, Power PC chip 1993

MOSAIC, Apple Newton

  • Netscape Navigator 1.0, Yahoo! 1994Palm computing
  • James Gosling: JAVA 1995Windows 95, Internet Explorer,Internet goes commercial
  • Windows 98, Apple\'s IMAC 1998Microsoft\'s court case
fourth generation computers15
Fourth-Generation Computers
  • Y2K Problem, Powermac G4 1999
  • Windows 2000 20001 GHZ processors
  • Mac OS X 2001Windows XP
  • Quantum Computer 2002
graphical user interface
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
network
Network
  • Defn: Two or more computers connect to exchange resources
    • Processing power
    • Storage
    • Access to a printer
    • Software resources
    • Messages
network18
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
computer organization

Computer Organization

Hardware and Software

Calvin College

computing systems
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, ...)
hardware cpu
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,
hardware ram
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).
hardware disk
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), ...
hardware the bus
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.
hardware cache
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.)

hardware summary

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.

software os

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.

software os28
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, ...

software applications
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)
software user programs
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.

putting it all together

Disk

CPU

RAM

Cache

OS

App

Bus

Putting it all together

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

putting it all together32

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.

putting it all together33

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.

the fetch execute cycle
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!

what is programming
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.

what kinds of statements do computers understand
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, ...

machine language ml
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

early computers
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!

a bright idea

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.

assembly languages
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
high level languages
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.

hll compilers

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.

slide44
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).
objectives in programming
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).
summary
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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