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COMP 102x

Introduction to Computing with Ja

Lecture One

T.C. Pong

Department of Computer Science & Engineerin

HKUST

Introducti

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Learning Objectives

Take a real-life problem and abstract out th

aspects necessary to solve it

Formulate formal solutions to well defined pr

using the logic of a programming language

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What is a well defined prob

A well-defined problem means that

a solution exists for the problem

the solution can be found in a finite num

Examples:

1 x 2 + 3

1 + 2 x 3

= 5

1 + (2 x 3) = 7

(1 + 2) x 3 = 9

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Learning Objectives

Take a real-life problem and abstract out the p

aspects necessary to solve it Formulate formal solutions to well defined prob

the logic of a programming language

Implement formal solutions using Java in an inte

development environment Have an understanding of basics of data abstract

the object-oriented framework

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Data Abstraction

Data Abstraction: To separate what can be dothe data from how it is represented.

For example, numbers can be represented in many

Arabic numerals:

0, 1, 2, 3, 4, 5, 6, 7, 8, 9

Roman numerals:

I, II, III, IV, V, VI, VII, VIII, IX, X Chinese numerals:

,,,,,,,,,,

Numbers in computers:

0, 1

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Computer Science

Computer Science is a discipline that studies the tand applications of computational systems.

Computational systems

Hardware aspect Designing and building computer systems in the fo

devices that are able to execute programs

Software aspect Studying the behavior of algorithms or computer p

determine whether they are correct and efficient

Application aspect Using computer systems to solve complex real-wor

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Hardware and Software

There are two important compone

the computer.

Hardware component

Software component

h

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The First Computer

The worlds first all-purpose elecomputer, ENIAC, was created

in 1946.

It weighted over 30 tons, conta

~18,000 vacuum tubes and occ

1800 ft2(or 180 m2) of space.

This image is from the Wikimedia Commons.

Source: U.S. Army

http://commons.wikimedia.org/wiki/Main_Pagehttp://commons.wikimedia.org/wiki/Main_Page

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Moores Law

Gordon Moore(1965): The

processing power

of computer chip

doubles

approximately

every 18 months.This image is from the Wikimedia Commons. Author: W

d

http://commons.wikimedia.org/wiki/Main_Pagehttp://commons.wikimedia.org/wiki/User:Wgsimonhttp://commons.wikimedia.org/wiki/User:Wgsimonhttp://commons.wikimedia.org/wiki/Main_Page

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Hardware perspective

ProcessingInput

devices

Outp

devic

Memory Storage d

A flowchart illustrates

the data flow through

different hardware

components

Stored program computer

C t l P i U it (CPU)

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Central Processing Unit (CPU)

The central processing unit (CPU) is the bcomputer

CPUs may appear anywhere

Desktop computers, mobile devices such as iPads

It retrieves instructions from the memoryperforms computation

It consists of two sub-units:

Arithmetic logic unit

Control unit

Processing

A ith ti L i U it d C t l U

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Arithmetic Logic Unit and Control U

Arithmetic logic unit

Basic arithmetic operations: + , - , x , /

Logical comparisons: = , > ,