BTKR1343 - Chapter 1 - Intro to Computer

7/30/2019 BTKR1343 - Chapter 1 - Intro to Computer

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LECTURE 1 1

BTKR1343

Introduction To Computers

And Programming Language


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LECTURE 1 2

In this chapter, you will:

Learn about different types of computers

Explore the hardware and software components

of a computer system

Learn about the language of a computer

Learn about the evolution of programming

languages Examine high-level programming languages

Objectives


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Objectives (cont.)

Discover what a compiler is and what it does

Examine a C++ program

Explore how a C++ program is processed

Become aware of Standard C++ and ANSI/ISO

Standard C++


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Why Program?

Computer programmable machine designed to

follow instructions

Program instructions in computer memory to

make it do something Programmer person who writes instructions

(programs) to make computer perform a task

SO, without programmers, no programs; withoutprograms, a computer cannot do anything


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LECTURE 1 5

Categories of Computers

Supercomputers

Mainframe computers

Minicomputers Microcomputers (personal computers)

Mobile computers


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Computer is an electronic device, with

two major components.

Computer

Hardware Software

Computer Components


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LECTURE 1 7

Hardware refers to the physical parts of the

computer that have mass (they can be touched)

Hardware for a typical computer system includethe following components

Computer Hardware


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Main Hardware Component

Categories:

1. Central Processing Unit (CPU)

2. Primary Storage or Main Memory

3. Auxiliary or Secondary Storage

4. Input Devices

5. Output Devices


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Main Hardware Component

Categories


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Central Processing Unit (CPU)

Brain of the computer

Comprised of:

Control Unit

Retrieves and decodes program instructions

Coordinates activities of all other parts of computer

Arithmetic & Logic Unit Hardware optimized for high-speed numeric

calculation

Hardware designed for true/false, yes/no decisions


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CPU Organization


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Main Memory

It is volatile. Main memory is erased when

program terminates or computer is turned off

Also called Random Access Memory (RAM) Organized as follows:

bit: smallest piece of memory. Has values 0 (off,

false) or 1 (on, true) byte: 8 consecutive bits. Bytes have addresses.


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LECTURE 1 13

Main Memory

Addresses Each byte in memory is

identified by a unique number known as an

address.

The number 149 is stored in the byte with the address 16,

and the number 72 is stored at address 23.


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Memory Cells

Address Contents-27.2

354

0.005-26

H

X

75.62

RTV 001

. . .

0

1

23

4

5

6

. . .

999

LECTURE 1


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Secondary Storage

Non-volatile: data retained when

program is not running or computer

is turned off

Comes in a variety of media:

magnetic: floppy disk, zip disk, hard

drive

optical: CD-ROM

Flash drives, connected to the USB

port


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Input Devices

Devices that send information to the

computer from outside

Many devices can provide input:

Keyboard, mouse, scanner, digital camera,

microphone

Disk drives and CD-ROM (Secondary

storage)


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Output Devices

Output is information sent from a computer

program to the outside world.

The output is sent to an output device

Many devices can be used for output:

Computer monitor and printer

Floppy, zip disk drives, writable CD drives

(Secondary storage)


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Computer Software

Software: refers to a program that residesand executes electronically on the hardware.

Software is divided into 2 categories

Software

System Software Application Software


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System Software

Related software that manages the systems resources

and control the operations of the hardware.

Normally supplied by the manufacturer of the computer.

Consists of utility programs and operating aids thatfacilitate the use and performance of the computer.

System programs take control of the computer, such as

an operating system.

Operating system are programs that manage the

computer hardware and the programs that run on them.

Examples: Windows, UNIX, Linux.


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Application Software

Programs that provide services (problem solution) tothe user.

Designed to perform a specific task (such as courseregistration or banking) OR a general-purpose task(such as word processing, eg. Ms Word).

May be acquired by purchasing off-the-shelf or by

designing for own purpose (custom made).

Off-the-shelf : General-purpose task. Prewritten and

ready to use. Custom made: Specific task. Written by in-house,

consulting firm or software house.


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Where are the application and

system software?


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Computing Environment

Personal Computing

Time-Sharing

Client / Server

Computing

Internet Computing


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Personal computing environment


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Time-sharing environment


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The client/server environment


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Internet

Server

Server

Clients (Browser)26

The internet environment


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Digital signals are sequences of 0s and 1s

Machine language: language of acomputer

Binary digit (bit): The digit 0 or 1

Binary code:

A sequence of 0s and 1s Byte:

A sequence of eight bits

The Language of a Computer


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Coding Schemes

ASCII (American Standard Code for

Information Interchange)

128 characters

A is encoded as 1000001 (66th character)

3 is encoded as 0110011


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Coding Schemes (cont.)

EBCDIC

Used by IBM

256 characters

Unicode

65536 characters

Two bytes are needed to store a character


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History Of Computer Languages

Computer language evolution

The only language understood by a computer is

machine language


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1.Machine Language

Computer only understand this language.

Series of 1s and 0s (binary numbers), such as

1011010000000101

Difficult to write.

Low level language


(cont.)


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Early computers were programmed in

machine language

To calculate wages = rates * hours

in machine language:

100100 010001 //Load

100110 010010 //Multiply

100010 010011 //Store


(cont.)


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2. Symbolic/Assembly Language Unique to particular computer.

Use mnemonics symbols. E.g. MUL Multiply

Easier to understand.


(cont.)


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Using assembly language instructions,wages = rates hours

can be written as:

LOAD rate

MULT hour

STOR wages

History Of Computer

Languages (cont.)


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3. High-Level Language

Portable to many different computers. Instruction are coded

Eg. COBOL (Business), FORTRAN (Scientific), BASIC,Pascal, C, C++, C#, Java etc.

Programmers use this to write programs.

Compiler: translates a program written in a high-levellanguage machine language

The equation wages = rate x hours can be writtenin C++ as:

wages = rate * hours;


(cont.)


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4. Natural Language

Like our natural language (such as English,French, or Chinese)

Its use is still quite limited.


(cont.)


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Programs and

Programming Languages

Types of languages:

High-level: closer to human

language

Low-level: used for

communication with computerhardware directly. Often writtenin binary machine code (0s/1s)directly.


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Some Well-Known High-Level

Programming Languages


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#include using namespace std;

int main()

{

cout


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Program Development

A computer understands a program only if theprogram is coded in its machine language.

Programmer have to write the program and

turn it into an executable (machine language)

code.

Programmer have to understand the problem

-> break into actions (write program)->

execute by the computer.


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From a High-level Program to an

Executable Code There are 4 steps in the process :a) Create and edit file containing the program (source

code) with a text editor.

b) Run preprocessor to process the preprocessordirectives (begin with #)

c) Run compiler to:

Check that the program obeys the rules

Translate into machine language (object code)

d) Run linker to connect hardware-specific code to

machine instructions, producing an executable code. Steps bc are often performed by a single command

or button click (compile using the compiler).

Errors detected at any step will prevent execution offollowing steps.


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Code

Code

Programmer

From a High-level Program to an Executable Code

Programmer


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Loader:

Loads executable code/program into main

memory

Execution:

The last step is to execute the program

Program Development (cont.)


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I t t d D l t


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Integrated Development

Environments (IDEs)

An integrated development environment,

or IDE, combine all the tools needed to

write, compile, and debug a program into asingle software application.

Examples are Microsoft Visual C++,

Borland C++ Builder, CodeWarrior, etc.

I t t d D l t


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Integrated Development

Environments (IDEs)


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ANSI/ISO Standard C++

C++ evolved from C

C++ designed by Bjarne Stroustrup at Bell

Laboratories in early 1980s

C++ programs were not always portable

from one compiler to another

In mid-1998, ANSI/ISO C++ language

standards were approved

P f i l Ethi f


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Professional Ethics for

Computer Programmers

Privacy and Misuse of Data

Computer Hacking

Plagiarism and Software Piracy Misuse of a Computer Resource

-the end-

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BTKR1343 - Chapter 1 - Intro to Computer