Computers and Digital Basics pot

fs Chapter Contents * Section B: Digital Devices * Section C: Digital Data Representation * Section D: Digital Processing * Section E: Password Security Chapter 1: Computers and Digi

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fs Chapter Contents

* Section B: Digital Devices

* Section C: Digital Data Representation

* Section D: Digital Processing

* Section E: Password Security

Chapter 1: Computers and Digital Basics

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Computer Basics

* Acomputer is a multipurpose device that accepts input,

processes data, stores data, and produces output, all according to a series of stored instructions

Computers produce out-

put on devices such as

= screens and printers

A computer accepts input

from an input device, such Data is processed in Art

as a keyboard, mouse, the CPU according to A computer $4

scanner, or digital camera instructionsthathave USS disks, =

been loaded intothe CDs, and "

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Dog

* Computer input is whatever is typed, cen

submitted, or transmitted to a computer

system

* Output is the result produced by a

computer

* Data refers to the symbols that represent

facts, objects, and ideas

* Computers manipulate data in many

ways, and this manipulation Is called

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Computer Basics

* Memory is an area of a computer that temporarily

holds data waiting to be processed, stored, or

output

* Storage is the area where data can be left ona

permanent basis when it is not immediately needed for processing

* A file is a named collection of data that exists on a

storage medium

* The series of instructions that tells a computer how

to carry out processing tasks is referred to as a

computer program

— Software

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Computer Basics

* A stored program means that a series of

instructions for a computing task can be loaded into a computer's memory

— Allows you to switch between tasks

— Distinguishes a computer from other simpler devices

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fs Computer Basics

* Application software is a set of computer

programs that helps a person carry out a task

* The primary purpose of system software is to

help the computer system monitor itself in order to function efficiently

— Operating system (OS)

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Personal Computers, Servers, Mainframes, and Supercomputers

* A personal computer is a microprocessor-

based computing device designed to meet the computing needs of an individual

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Personal Computers, Servers,

Mainframes, and Supercomputers

X The term workstation has two meanings:

— An ordinary personal computer that is connected

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BW example: Workstation Computer

1 Example: Workstation Computer

* http://www.dell.com/

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Personal Computers, Servers, Mainframes, and Supercomputers

* A videogame console, such as

Nintendo’s Wii, Sony's PlayStation,

or Microsoft's Xbox, are not

generally referred to as personal

computers because of theirh -œz>

dedicated game devices

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* A mainframe computer (or simply a mainframe) is a large

and expensive computer capable of simultaneously

processing data for hundreds or thousands of users

* A computer falls into the supercomputer category if it is, at

the time of construction, one of the fastest computers in the world

— Acompute-intensive problem is one that requires massive amounts

of data to be processed using complex mathematical calculations

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Mainframes, and Supercomputers

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The Digital Revolution

* A computer network is a group of computers linked

by wired or wireless technology to share data and resources

* The Web is a collection of linked documents,

graphics, and sounds that can be accessed over the Internet

* Cyberspace is a term that refers to entities that exist largely within computer networks

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4]

PDAs, Portable Players,

and Smart Phones ¬

A PDA (personal digital assistant) is a pocket-sized digital

appointment book with a small qwerty keyboard or a touch-

sensitive screen, designed to run on batteries and be used

while holding it

A handheld computer is essentially a PDA enhanced with

features such as removable storage, e-mail, Web access, voice communications, built-in camera, and GPS

A smart phone, which in addition to voice communication,

includes features such as full qwerty keypad, text messaging,

e-mail, Web access, removable storage, camera, FM radio,

digital music player, and software options for games, financial management, personal organizer, GPS, and maps

iPods and similar devices are classified as portable media players because their main strength is playing music, showing videos, and storing photos

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PDAs, Portable Players,

and Smart Phones

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"SECTION (>

10114 Tinie VN oa

Data Representation Basics

Representing Numbers, Text, and Pictures

Quantifying Bits and Bytes

Circuits and Chips

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Data Representation

* Data representation refers to the form in which

data is stored, processed, and transmitted

* Digital devices work with distinct and separate

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—ASCIl, Extended ASCII, ina

process of converting at aar0

analog data into digital

format

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fs Example: Binary Representation

* Representing data with binary values has

been around for a long time For example, Morse code uses a series of short and long signals to represent values

* http://en.wikipedia.org/wiki/Morse_code

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Quantifying Bits and Bytes

Kilobit 1,024 or 219 bits

Kilobyte 1,024 or 210 bytes Megabit 1,048,576 or 220 bits Megabyte 1,048,576 or 220 bytes

Gigabit Gigabyte Terabyte

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Programs and Instruction Sets

* Computers, portable media players, handheld

computers, and smart phones all work with digital

data

* Computer programmers create programs that

control digital devices These programs are usually written in a high-level programming language

* The human-readable version of a program, like the one above, created in a high-level language by a

programmer is called source code

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Conv.vbs

int fahrenheit = 0; 10100100101

Processor Interpreter

High-level language instructions

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for (I=0; l<=100; I++) sum += 1 * 1;

printf (“The sum 0 100=%d\n",sum);

00100111101111011111111111100000 I0101111101111110000000000010100 I0I01111101001000000000000100000 IOI0I111110I1001010000000000100100 I0101111101000000000000000011000 I0I01111101000000000000000011100

00000000000000000111100000010010

00000011000011111100100000100001 00010100001000001111111111110I111 IOI0I11I1I1I101110010000000000011000

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Authentication Protocols

* Security experts use the term authentication

protocol to refer to any method that confirms a person's identity using something the person

knows, something the person possesses, or

something the person Is

— Auser ID is a series of characters—letters and possibly numbers or special symbols—that becomes a person's unique identifier

— Apassword is a series of characters that verifies a user

ID and guarantees that you are the person you claim to

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Authentication Protocols

User Name & Password

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Password Hacks

* When someone gains unauthorized access to your personal data and uses itt illegally, it is called identity theft

* Hackers can employ a whole range of ways to steal passwords

* A dictionary attack helps hackers guess your

password by stepping through a dictionary containing thousands of the most commonly used

passwords

* The brute force attack also uses password-cracking software, but its range is much more extensive than the dictionary attack

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fs Password Hacks

* If hackers can’t guess a password, they can

use another technique called sniffing, which intercepts information sent out over computer networks

* A keylogger (or keystroke logger) is software that secretly records a user’s keystrokes and sends the information to a hacker

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® Do notuse a password based on public information such as your phone number, Social Security number, driver’s license number, or birthday Hackers can easily find this information, and other personal facts such as names of your spouse, children, or pets

® Avoid passwords that contain your entire user ID or part of it Auser 1D of bjeffe coupled with a password of bjeffe123 is an easy target for password thieves

® Steer clear of words that can be found in the dictionary, including foreign words Dictionary attacks can utilize foreign language dictionaries Even common words spelled backwards, such as drowssap instead of password, are not tricky enough to fool password-cracking software

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Password Security

* Strive to select a unique user ID that you can

use for more than one site

* Maintain two or three tiers of passwords

Tier 1: High security Tier 2: Low security

Password: BBx98$$NN26 Password: Rover

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Password Security

* A password manager is utility software that

enerates secure passwords and stores

them along with user IDs and their

Recently Used)

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