King Fahd University of Petroleum & Minerals College of Computer Science & Engineering

1. King Fahd University of Petroleum & Minerals College of Computer Science & Engineering Information & Computer Science Department ICS102 - Introduction to computing Lecture 1 : Introduction

2. Components of a Personal Computer • Questions : • what are the input devices ? • what are the output devices ? ICS102: Intro To Comp

3. Motherboard A motherboard,provides the electrical connections by which the other components of the system communicate and hosts the central processing unit as well as other subsystems and devices. ICS102: Intro To Comp

4. Motherboard example : Acer E360 ICS102: Intro To Comp

5. CPU (Central Processing Unit) The Central Processing Unit (CPU) or processor is the portion of a computer system that carries out the instructions of a computer program and is the primary element carrying out the computer's functions. Example: (3 + 2) = 5 In an addition operation, the arithmetic logic unit (ALU) will be connected to a set of inputs and a set of outputs. The inputs provide the numbers to be added, and the outputs will contain the final sum. 3 5 2 ICS102: Intro To Comp

6. CPU memory Registers Cache Main memory (RAM): Data has to be in main memory so that CPU can access it Volatile: lost when program exits; computer shuts off Hard Disk, CD, etc. Persistent This is where you keep the data for long-term storage Memory  Memory refers to computercomponents, devices, and recording mediathat hold digital dataused for computing for some interval of time.  There are mainly three types of memory : ICS102: Intro To Comp

7. Main Memory … Cell Address Memory is divided into Many memory locations (cells) 1002 1003 1004 Each memory cell has a numeric address, which uniquely identifies it 1005 Each cell contains a data value, e.g. 22 ICS102: Intro To Comp

8. Main Memory … ICS102: Intro To Comp

9. Main Memory … The word “Hello.” stored in 6 memory cells ICS102: Intro To Comp

10. Memory units : Bits and Bytes • Bit -- most basic unit of memory • 1 or 0, on or off • 1 Byte = 8 bits • In a computer, data values are stored as a sequence of bits 1004 2 1004 00000010 1005 1005 7 00000111 ICS102: Intro To Comp

11. Program / CPU / Memory Interaction Example: Input read a number from keyboard Add 1 to it Output it on screen CPU RAM 1 RAM 2 2 2 1 1 Monitor Keyboard ICS102: Intro To Comp

12. What is programming?

13. What is a program? A (software) program is a list of instructions intended to a computer The list must be ordered correctly A program has inputs and outputs Each instruction tells the computer to do something (an action, a calculation, a comparison) ICS102: Intro To Comp

14. Program Execution A program tells the CPU how to manipulate and/or move information Programming is about processing information Take some input, manipulate it in some way, and produce a particular output Program Manipulation Inputs Outputs ICS102: Intro To Comp

15. Example 1 : Recipe for Scrambled Eggs Ingredients (Inputs) : two eggs, tablespoon of oil, salt Instructions (program): Add oil to pan Heat pan on stove Crack eggs into pan Add salt Mix until light and flakey Output: scrambled eggs ICS102: Intro To Comp

16. Example 2 : Currency Exchange Input: Amount Source Currency Desired Currency Instructions Look up in table current exchange rate for the selected currencies Calculate result as amount * exchange rate • Output: result Task : convert an amount of money in some currency (e.g. US Dollars) to another one (e.g. Saudi Riyals). ICS102: Intro To Comp

17. Programming language A programming language is the language used to write programs A programming language employs a set of rules that dictate how the words and symbols can be put together to form valid program statements A programming language has a syntax and semantics There are several types of languages (functional, Object-Oriented, etc.) In this course we focus on Java programming language. ICS102: Intro To Comp

18. Java • Javais a programming languageoriginally developed by James Goslingat Sun Microsystems • It was first released in 1995. • The language derives much of its syntaxfrom C and C++. • But has a simpler object modeland fewer low-level facilities than C and C++. ICS102: Intro To Comp

19. Why Java ? Currently, Java is the most popular language in the world ! ICS102: Intro To Comp

20. Why Java ? • Simple • Get started quickly • Concise • Write less code • Object-oriented • Better quality code • Portable • Architecture neutral (write once run anywhere) • Secure • More appropriate for Internet ICS102: Intro To Comp

21. Portability of Java Classical model : Java model : ICS102: Intro To Comp

22. Portability of Java Write once, run anywhere: Because applications written in the Java programming language are compiled into machine-independent bytecodes, they run consistently on any Java platform. ICS102: Intro To Comp

23. A Java Program A Java program consists of one or more classes A Java class consists of one or more methods A Java method consists of one or more statements A Java Program Java classes Java Methods ICS102: Intro To Comp

24. A Java Program A Java program resides in one or more files. The file name of a Java program has extension .java. One of the classes of a Java program is called the driver class. The name of the driver class must be the same as the name of its Java file. (Java is case sensitive. So EX1 is different from ex1.) The diver class must contain a method called main. The execution of Java program starts from the main method of the driver class. ICS102: Intro To Comp

25. Example of a Java Program ICS102: Intro To Comp

26. Example of a Java Program Class name Main method Class body Instruction ICS102: Intro To Comp

27. Example of a Java Program Also notice: Curly braces { } ICS102: Intro To Comp

28. Example of a Java Program Also notice: Curly braces { } Parentheses ( ) ICS102: Intro To Comp

29. Example of a Java Program Also notice: Square brackets [ ] Curly braces { } Parentheses ( ) ICS102: Intro To Comp

30. Example of a Java Program Also notice: A pair of braces { } define a block ICS102: Intro To Comp

31. Compiling and running a program • Type in your program • Save the program • Store all your files in one directory for now • Give the program the same name as the class • Compile the program • this produces a .class file • Translates the program into something the computer can understand and execute (Java bytecode) • Run the program • Observe the result and adjust the program if necessary ICS102: Intro To Comp

32. Public class Adven /* This program is an Arit */ public static void main /* Program statements g System.out.print(“Wel } } Text Editor Adventure.java Edit Public class /* ICS102: Intro To Comp

33. Compile - With Errors Public class Adven /* This program is an Arit */ public static void main /* Program statements g System.print(“Welcome } } Compiler Adventure.java Errors and Warnings ------------------- Error : The method print( String) is undefined for Type System ICS102: Intro To Comp

34. Compile - Success Public class Adven /* This program is an Arit */ public static void main /* Program statements g System.out.print(“Wel } } 001011010001011101 1011010001011101110 1010001011101110101101000101110111010110100010111011101011010001011101110101101000101110111000101110111010110100010111011100101110111010110100010111011100101110111010110100010111011100101110111010110100010111011100101110111010110100010111011100101110 Compiler Adventure.java Adventure.class ICS102: Intro To Comp

35. Fred 1 Welcome to the Arithm The date is Monday Sep What is your name?Fred Well Fred, after a day The cube appears to be You find a Green door, The door closes behind There is a feel of mat Adventure Run Program ICS102: Intro To Comp

36. End