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King Fahd University of Petroleum & Minerals College of Computer Science & Engineering. Information & Computer Science Department. ICS102 - Introduction to computing. Lecture 1 : Introduction. Components of a Personal Computer. Questions : what are the input devices ?

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

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#### Presentation Transcript

King Fahd University of Petroleum & Minerals

College of Computer Science & Engineering

Information & Computer Science Department

ICS102 - Introduction to computing

Lecture 1 : Introduction

Components of a Personal Computer

• Questions :

• what are the input devices ?

• what are the output devices ?

ICS102: Intro To Comp

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

Motherboard example : Acer E360

ICS102: Intro To Comp

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

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

### Main Memory …

Cell

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

Main Memory …

ICS102: Intro To Comp

Main Memory …

The word “Hello.” stored in 6 memory cells

ICS102: Intro To Comp

### 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

### Program / CPU / Memory Interaction

Example:

Input read a number from keyboard

Output it on screen

CPU

RAM

1

RAM

2

2

2

1

1

Monitor

Keyboard

ICS102: Intro To Comp

## What is programming?

### 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

### Program Execution

A program tells the CPU how to manipulate and/or move information

Take some input, manipulate it in some way, and produce a particular output

Program

Manipulation

Inputs

Outputs

ICS102: Intro To Comp

### Example 1 : Recipe for Scrambled Eggs

Ingredients (Inputs) : two eggs, tablespoon of oil, salt

Instructions (program):

Heat pan on stove

Crack eggs into pan

Mix until light and flakey

Output: scrambled eggs

ICS102: Intro To Comp

### 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

### 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

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

### Why Java ?

Currently, Java is the most popular language in the world !

ICS102: Intro To Comp

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

Portability of Java

Classical model :

Java model :

ICS102: Intro To Comp

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

### 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

### 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

### Example of a Java Program

ICS102: Intro To Comp

### Example of a Java Program

Class name

Main method

Class body

Instruction

ICS102: Intro To Comp

### Example of a Java Program

Also notice:

Curly braces { }

ICS102: Intro To Comp

### Example of a Java Program

Also notice:

Curly braces { }

Parentheses ( )

ICS102: Intro To Comp

### Example of a Java Program

Also notice:

Square brackets [ ]

Curly braces { }

Parentheses ( )

ICS102: Intro To Comp

### Example of a Java Program

Also notice:

A pair of braces { } define a block

ICS102: Intro To Comp

### Compiling and running a 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

/*

This program is an Arit

*/

public static void main

/* Program statements g

System.out.print(“Wel

}

}

Text Editor

### Edit

Public class

/*

ICS102: Intro To Comp

### Compile - With Errors

/*

This program is an Arit

*/

public static void main

/* Program statements g

System.print(“Welcome

}

}

Compiler

Errors and Warnings

-------------------

Error : The method print(

String) is undefined for

Type System

ICS102: Intro To Comp

### Compile - Success

/*

This program is an Arit

*/

public static void main

/* Program statements g

System.out.print(“Wel

}

}

001011010001011101

1011010001011101110

1010001011101110101101000101110111010110100010111011101011010001011101110101101000101110111000101110111010110100010111011100101110111010110100010111011100101110111010110100010111011100101110111010110100010111011100101110111010110100010111011100101110

Compiler

ICS102: Intro To Comp

Fred

1

Welcome to the Arithm

The date is Monday Sep

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