1. COSC 1P02 Intro. to Computer Science 1.1 Cosc 1P02 Week 1 Lecture slides "If a man does his best, what else is there?” General George S. Patton (1885-1945)

2. COSC 1P02 Intro. to Computer Science 1.2 COSC 1P02  Audience  planning to major in COSC  Staff  instructors: Dave Hughes (J312) & Dave Bockus (J324)  mentor: Baoling Bork (J304)  tutorial leader:  lab demonstrators:  Lectures (AS216), labs (J301), tutorials (AS203)  Web  COSC: http://www.cosc.brocku.ca/http://www.cosc.brocku.ca/  COSC 1P02: http://www.cosc.brocku.ca/offerings/cosc1p02/http://www.cosc.brocku.ca/offerings/cosc1p02/  Email  Dave Hughes: hughesd@brocku.cahughesd@brocku.ca  Dave Bockus: bockusd@brocku.cabockusd@brocku.ca  Succeeding in COSC 1P02  labs/assignments

3. COSC 1P02 Intro. to Computer Science 1.3 Course Content and Procedures  All course documents available through Computer Science Website:  www.cosc.brocku.ca/Offerings/1P02/ www.cosc.brocku.ca/Offerings/1P02/  COSC home page: www.cosc.brocku.cawww.cosc.brocku.ca  Outline  Instructional labs  lab participation  Assignment preparation  Help Desk (J304)  submission (outside J332)  return (J333)  plagiarism  Exams/tests  lab vs written  course procedures  plagiarism plagiarism  students with computers  Software: JCreator or Dr. JavaDr. Java  Libraries  BasicIO  TurtleGraphics  Media

4. COSC 1P02 Intro. to Computer Science 1.4 Class Room  Ground Rules  Lecture conduct  Cell Phones  Laptops  Contact information:  Email messages only accepted from a Brock server.  Dave Bockus  Open Door Policy (J324, Day Section)  E-mail bockusd@brocku.ca  MSN bockusd@hotmail.com

5. COSC 1P02 Intro. to Computer Science 1.5 Computer Science What is it?  study of computer hardware and algorithms and data structures and how they fit into information systems.  computer  programmable machine.  processes data into information.  Algorithm  well-defined sequence of steps to produce an outcome  programming language  Java Hardware Data InInfo Out Algorithm Software

6. COSC 1P02 Intro. to Computer Science 1.6 Hardware Components  processor (CPU)  control unit (CU)  controls system  follows instructions  arithmetic logic unit (ALU)  performs operations (e.g. +, -, =, <)  main memory (RAM)  volatile  input devices  transformation  keyboard, scanner, sensor

7. COSC 1P02 Intro. to Computer Science 1.7

8. COSC 1P02 Intro. to Computer Science 1.8 Hardware Components.  output devices  transformation  monitor, printer, actuator  auxiliary storage  hard disk, floppy disk, CD-ROM, DVD, Data Keys  communications  Networks ( wired, broadband)  modem, cable modem

9. COSC 1P02 Intro. to Computer Science 1.9 Data Representation  switches—bi-stable devices  binary system  positional (like decimal)  bit  byte  megabyte (MB)  memory organization  storage cell  address  store(write)/fetch(read) Address, where the info is located. Data, what is stored.

10. COSC 1P02 Intro. to Computer Science 1.10  All information is represented in binary code  numbers  characters  coding scheme  sound, images  Digitization  Important: bytes of data only differ in how they are interpreted.  The same byte can be viewed as:  Simple representation  Numbers (integers and floats)  Characters (abc…)  Part of Complex Objects  Pictures, sounds, video  Program  Machine Code which instructs the hardware.  Its all in the interpretation Data Representation (2)

11. COSC 1P02 Intro. to Computer Science 1.11 Instruction Processing  machine language  Opcode (operation code)  Operand (source data to be used in the operation)  CPU  registers  Special Registers IAR, IR  bus  machine (fetch/decode/execute) cycle  fetch  decode  execute  system clock  1 megahertz (Mhz) = 1,000,000 cycles/second

12. COSC 1P02 Intro. to Computer Science 1.12

13. COSC 1P02 Intro. to Computer Science 1.13

14. COSC 1P02 Intro. to Computer Science 1.14

15. COSC 1P02 Intro. to Computer Science 1.15 Fetch/Decode Cycle

16. COSC 1P02 Intro. to Computer Science 1.16 Coding Schemes

17. COSC 1P02 Intro. to Computer Science 1.17 Machine Language Assembly Language  First generation  One-to-one correspondence with hardware function  Binary representation  Operator (opcode)  Operands  Developed into Assembly by allowing mnemonics to represent the actual machine instructions.  made life easier for the programmers.

18. COSC 1P02 Intro. to Computer Science 1.18 High-level Language  Closer to problem domain  One-to-many translation  Code much easier to write and understand  Made writing large programs much easier.  Required:  Compiler  Takes source program  Converts to object program {something the machine can understand}  Libraries  linker  Compile time vs Link time vs Execution time

19. COSC 1P02 Intro. to Computer Science 1.19 Software  Software  computer program  instructions for machine execution  Compiler  Translation of a high level language into machine language.  Program preparation  edit  editor  compile  compiler  syntax errors  link  add in resources (code) from library  execute  execution (logic) errors (bugs)  Development environment (IDE, e.g. DrJava, JCreator)

20. COSC 1P02 Intro. to Computer Science 1.20 Computer Programming

21. COSC 1P02 Intro. to Computer Science 1.21 Java  Gosling (1990-92)  Originally for consumer electronics  embedded systems  Platform independence  Object-oriented  programming as modeling  Java as a better C++  Execution of Java programs  platform independence  machine language?  Java bytecode  Java interpreter

22. COSC 1P02 Intro. to Computer Science 1.22 Java Programming Concepts  library (package)  e.g. Media  collection of useful classes  imported to be used  class  e.g. Turtle  definition of a kind of entity (object)  defines operations (methods) entities can perform  object  one entity from a class (a turtle)  created using new

23. COSC 1P02 Intro. to Computer Science 1.23  variable  e.g. yertle  name that refers to an object or value  method  e.g. forward  an operation that can be performed by an object  statement  a line of Java code  method call statement  request for an object to perform a method  object.methodName(parameters)  e.g. yertle.forward(40)

24. COSC 1P02 Intro. to Computer Science 1.24 Turtle Graphics  Simple graphics facility  Derived from Logo  TurtleDisplayer  a class in the BasicIO library  canvas of 300 by 300 drawing units  Turtle  a class in the Media library  draws on a canvas  Drawing a square  create displayer  create turtle  put turtle on canvas  put pen down  draw line  turn corner  repeat

25. COSC 1P02 Intro. to Computer Science 1.25 Assembly and Machine Language

26. COSC 1P02 Intro. to Computer Science 1.26 Executing an Assembly Language Program

27. COSC 1P02 Intro. to Computer Science 1.27 Executing a High-Level Language Program

28. COSC 1P02 Intro. to Computer Science 1.28 Turtle Displayer  This is equivalent to a piece of paper which the turtle will draw on.  Create the Displayer  Put the turtle on the Displayer  This also implies we can have more then 1 turtle on the same displayer.  Displayer and Turtle are resources provided by libraries.  We do not make the paper we use. We let someone else do this for us.  Code is linked in to our program  If you want a piece of paper you have to have a access to it.  Same for a pencil  Import statement allows us access to these libraries.

29. COSC 1P02 Intro. to Computer Science 1.29 A Java Program  Draw a square  Framework  a program is a class  code for a class is stored in a file  a class is part of a package  establish (import) environment (libraries)  define names (variables) being used  constructor is a method that is executed when an object is created  contains actions (statements) to be performed  main method creates an instance of the DrawSquare class to begin execution

30. COSC 1P02 Intro. to Computer Science 1.30 package Example_2_1; import BasicIO.*; import Media.*; import static java.lang.Math.*; public class DrawSquare { private TurtleDisplayer display; // display to draw on private Turtle yertle; // turtle to do drawing public DrawSquare ( ) { display = new TurtleDisplayer(); yertle = new Turtle(); display.placeTurtle(yertle); yertle.penDown(); yertle.forward(40); yertle.right(PI/2); yertle.forward(40); yertle.right(PI/2); yertle.forward(40); yertle.right(PI/2); yertle.forward(40); yertle.right(PI/2); yertle.penUp(); display.close(); }; // constructor public static void main ( String[] args ) { new DrawSquare(); }; } Import, make libraries visible. Declare the variable display & yertle. Create the Objects we need to use, Drawing Surface -> display and the Turtle -> yertle. Use yertle by calling methods. Put the Turtle on the Surface. Basic Program Components

31. COSC 1P02 Intro. to Computer Science 1.31 Draw Square Program Flow package Example_2_1; import BasicIO.*; import Media.*; import static java.lang.Math.*; /** This class is a program to draw a square using Turtle Graphics. * * @author D. Hughes * * @version 1.0 (July 2007) * * new concepts: java program structure, declarations, constructor, object creation, * object assignment, method calls, turtle displayer, turtle graphics */ public class DrawSquare { private TurtleDisplayer display; // display to draw on private Turtle yertle; // turtle to do drawing public DrawSquare ( ) {/** The constructor. */ display = new TurtleDisplayer(); yertle = new Turtle(); display.placeTurtle(yertle); yertle.penDown(); yertle.forward(40); yertle.right(PI/2); yertle.forward(40); yertle.right(PI/2); yertle.forward(40); yertle.right(PI/2); yertle.forward(40); yertle.right(PI/2); yertle.penUp(); display.close(); }; // constructor public static void main ( String[] args ) { new DrawSquare(); }; } Program starts by creating a new Square Object Variables declared in the class body are called instance variables. Each new Object will have its own instance variables. display yertle Yertle is instructed to put its pen down and draw a square. Wait until the display close button is pressed, then exit Constructor finishes and program ends

32. COSC 1P02 Intro. to Computer Science 1.32 TurtleDisplayer Methods

33. COSC 1P02 Intro. to Computer Science 1.33 Turtle Methods

34. COSC 1P02 Intro. to Computer Science 1.34 The end