Introduction to Computers, Problem Solving, and Programming

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Introduction to Computers, Problem Solving, and
Programming

• Chapter 1

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1.1 Overview of Computers

• Computer - A device for counting or computing
• Dr. John Atanasoff - 1st computer.
• ENIAC 1946 at U of Penn
• Dr. John Von Neumann - Princeton
• Stored program concept
• Memory rather than wires and switches.
• Computing History

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Overview of Computers

• Von Neumann architecture basis for today's
  computers
• VLSI Technology made computers affordable, small
  and available to the public
• How programming has changed over time

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1.2 Computer Hardware

• Every computer is organized roughly into six
  parts
• CPU - central processing unit
• Where decisions are made, computations are
  performed, and input/output requests are
  delegated
• Main Memory
• Stores information being processed by the CPU
• Secondary Memory
• Stores data and programs

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Computer Hardware

• Input devices
• Allows people to supply information to computers
• Output devices
• Allows people to receive information from
  computers
• Network connection
• Modems / Ethernet interface

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Computer Components
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Main Memory

• Address

• Contents

-27.2
0

• 354

1

• .005

75.62
1024
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Main Memory

• Stores
• programs
• data
• results
• Types
• RAM
• ROM

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Secondary Memory Storage

• Semi permanent data-storage capability
• Tape or Disk
• Hard disk
• CD ROM
• Secondary memory has much more storage capacity

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CPU

• Brains of the computer
• Arithmetic calculations are performed using the
  Arithmetic/Logical Unit or ALU
• Control unit decodes and executes instructions
• Arithmetic operations are performed using binary
  number system

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CPU

• Fundamental building block is a switch
• Switches are made from ultrasmall transistors
• Examples
• The Pentium processor contains about three
  million transistors
• The Pentium Pro has about 5.5 million
  transistors

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Input / Output Devices

• Accessories that allow computer to perform
  specific tasks
• Receiving information for processing
• Return the results of processing
• Store information
• Common input and output devices
• Printer Joystick CD-ROM
• Keyboard Monitor

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Computer Networks

• LAN - Local area network
• Organizational
• WAN - Wide area network
• Internet

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World Wide Web

• Introduced 1989
• Developed by CERN
• European Laboratory for Particle Physics
• Web browser
• GUI
• Netscape
• IE

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1.3 Computer Software

• Application software
• Programs designed to perform specific tasks that
  are transparent to the user
• System software
• Programs that support the execution and
  development of other programs
• Two major types
• Operating systems
• Translation systems

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Application Software

• Application software is the software that has
  made using computers indispensable and popular
• Common application software
• Word processors
• Desktop publishing programs
• Spreadsheets
• Presentation managers
• Drawing programs

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Operating System

• Controls and manages the computing resources
• Important services that an operating system
  provides
• File system
• Commands that allow for manipulation of the file
  system
• Ability to perform input and output on a variety
  of devices
• Management of the running systems
• Examples
• MSDOS , Windows , Unix

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Programming Languages

• Machine Language
• Native tongue of the computer
• Binary 0s and 1s that specify what to do
• 0010 0000 0000 0100
• 1000 0000 0000 0101
• 0011 0000 0000 0110
• High - Level Languages
• Resemble human language (C, C, Pascal)
• cost price tax

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Programming Languages

• Language Standard
• Syntax (grammatical form) (rules)
• Portable
• programs used without modification
• Source Program
• Object Program
• Executable Program

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Object Oriented Programming

• OOP derived from C
• Bjarne Stroustrup
• Popular because of reuse
• Classes
• Objects
• Organized in a Hierarchy
• Super Classes
• Sub Classes

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OO Programming and Structured Programming

• Object-oriented design and programming supports
  good software engineering
• Object-oriented design promotes thinking about
  software in a way that models the real world

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OO Programming and Structured Programming

• Algorithms are the basis for the procedural
  sections (Structured Programs)
• Highly structured
• Top-down design
• Step-wise refinement

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Object Oriented Design

• Abstraction
• Extract the relevant properties of an object
  while ignoring inessential details
• Encapsulation
• Breaking down an object into parts, hiding and
  protecting its essential information, and
  supplying an interface to modify the information
  in a controlled and useful manner

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Object Oriented Design

• Modularity
• Dividing an object into smaller pieces or modules
  such that the object is easier to understand and
  manipulate
• Hierarchy
• Ranking or ordering of objects based on some
  relationship between them

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Abstraction

• Process of extracting only the relevant
  properties of an object
• Extracted properties define a view of the object

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Abstraction

• Car dealer views a car from selling features
  standpoint
• Price, warranty, color, etc.
• Mechanic views a car from systems maintenance
  standpoint
• Oil, oil filter, spark plugs, etc.

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Encapsulation

• Breaking down an object into parts, hiding and
  protecting its essential information, and
  supplying an interface to modify the information
  in a controlled and useful manner
• By hiding the information its representation and
  content can be changed without affecting other
  parts of the system

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Encapsulation

• Example - car radio
• Controlled by switches and knobs
• The details of how it works is hidden

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Modularity

• Dividing an object so that the object holds
  useful information and it is easier to understand
• Most complex systems are modular
• Cooling System
• Ignition System
• Fuel System

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Modularity

• Example - Automobile can be decomposed into
  subsystems
• Cooling system
• Radiator
• Thermostat
• Water pump
• Ignition system
• Battery
• Starter
• Spark plugs

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Hierarchy

• Ranking or ordering of objects based on some
  relationship between them
• Hierarchies facilitate understanding complex
  organizations and systems
• Example - a company hierarchy helps employees
  understand the structure of their company and
  their positions

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OO Classes

• Later we will use data abstractions
• C language
• Will apply OO techniques
• Structured Programming
• Object Oriented Programming
• Model our own objects or abstractions

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1.4 Processing a High-Level Language Program

• Set of programs used to develop software
• A key component of a is a translator
• Types of translators
• Compiler
• Linker
• Examples
• g, Borland C , Microsoft Visual C

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Processing a Program

• Editor used to enter the program
• Source program (file.cpp)
• UNIX vi text editor
• Compiler translates the source program
• Displays syntax errors (not descriptive)
• Linker/Loader to combine object file with other
  object files
• Executable program

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Processing a Program

• Major activities
• Editing
• Compiling
• Linking with pre-compiled files
• Object files
• Library modules
• Loading and executing
• Viewing the behavior of the program

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Process Cycle
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1.5 Software Development Method

• Problem Analysis - (Correct Problem)
• Identify data objects
• Goal to model properties
• Determine Input / Output data
• Constraints on the problem
• Design
• Decompose into smaller problems
• Top-down design (divide and conquer)
• Develop Algorithm (Desk check)

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Software Development Method

• Implementation
• Writing the algorithm
• Testing
• Verify the program meets requirements
• System and Unit test
• Documentation
• Key part in the development process

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Software Development Method

• Software engineering
• Area of computer science concerned with building
  large software systems
• Challenge
• Tremendous advances in hardware have not been
  accompanied by comparable advances in software

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Software Engineering Goals

• Reliability
• An unreliable life-critical system can be fatal
• Understandability
• Future development becomes very difficult if
  software is hard to understand
• Cost Effectiveness
• Cost to develop and maintain should not exceed
  profit

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Software Engineering Goals

• Adaptability
• System that is adaptive is easier to alter and
  expand
• Reusability
• Improves reliability and maintainability, and
  reduces development costs

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1.6 Applying the Software Development Method

• Case Study Converting Miles to Kilometers
• Problem  Your summer surveying job requires you
  to study some maps that give distances in
  kilometers and some that use miles. You and your
  coworkers prefer to deal in metric measurements.
  Write a program that performs the necessary
  conversion.

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Applying the Software Development Method

• Analysis  The first step in solving this problem
  is to determine what you are asked to do. You
  must convert from one system of measurement to
  another, but are you supposed to convert from
  kilometers to miles, or vice versa? The problem
  states that you prefer to deal in metric
  measurements, so you must convert distance
  measurements in miles to kilometers.

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Applying the Software Development Method

• Design  The next step is to formulate the
  algorithm that solves the problem. Begin by
  listing the three major steps, or sub problems,
  of the algorithm.
• Implementation  To implement the solution, you
  must write the algorithm as a C program.
• Testing  How do you know the sample run is
  correct?

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1.7 Professional Ethics for Computer Programmers

• Privacy and Misuse of Data
• Computer Hacking
• Plagiarism and Software Piracy
• Misuse of a Computer Resource