I.T.C - lecture2

8/3/2019 I.T.C - lecture2

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Components of Computer


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Input

Any thing given tothe computer isknown as input

such as instructionsor data

Converts raw datainto electronic form


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3

Input Devices: Giving Commands

Input devices are types of hardware that enable you

to get programs, data, commands, and responses

into the computers memory

Keyboard

Mouse

Stylus


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Keyboard

Traditional Looks like typewriter with

extra keys

Non-traditional

It is used for specific purpose

Fast food restaurants

Each key represents a food

item rather than a character


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Keyboard

Main Keyboard

Typewriter keys

Special command keys


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Keyboard

Numeric Keys Num Lock toggle On n umeric data & math

symbols

Off cursor movement Cursor Movement Keys

Function Keys F1-F12

Give commands

Software specific

F1 is the help key in most programs.


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Keyboard

Special Keys

Enter

Esc

Alt

CtrlCaps Lock

Shortcut

Windows

Shift


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Shift:

Output a capital letter or symbol when pressed along withan alphanumeric key.

Select text for editing when pressed along with cursor

movement keys.

Ctrl:Produces different results depending on the program youare using.

Ctrl key combinations provide shortcuts for menu

commands.

Alt:Produces different set of results

In windows, Alt key combinations enable you to navigate

menus and dialog boxes without using mouse.


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Enhanced / Extended

Keyboard

Types of Keyboard

Enhanced orExtended keyboard Typically 101 keys

laid out in the QWERTY fashion; connected to the

computer by a serial cable Cordless keyboard Uses infrared or radio wave

signals


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Ergonomic Keyboard

Types of Keyboard

Ergonomic keyboard

Designed to help prevent damage to nerve tissues in the

wrist and hand due to repeated motion. It enables the users hands to remain positioned

correctly while reducing bending and strain

Designed for people who type for extended period and

suffer from wrist and hand fatigue.


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Pointing Devices

A mouse is a small, lightweight input device.

It is also called pointing device

Position a pointer / cursor on the screen Controls drawing instruments in graphics

applications


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Pointing Devices

Mouse

Types

Mechanical Optical

Wireless

Features

Palm-sized 1 or 2 buttons

Wheel


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Mechanical

1. Contain a small rubber ball.

2. Ball rolls inside the case when you move the mouse ona flat surface.

3. Rollers and sensors send signals to the computer,

telling distance, direction and speed of ball.

Optical

1. Emits a beam of light from its underside.

2. Uses the lights reflection to judge the distance,

direction and speed of its travel.

Wireless

1. Give computer users cordless accessibility to their mice

and to interact with their computer.


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PS/2 Port

The color-coded PS/2 connection ports:

Purple for keyboard

Green for mouse


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Other Types ofPointing Devices

Joystick

Touch Pad

Touch

Screen

Trackball

PointingStick

Pen


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Other Pointing Devices

Trackball Upside-down mouse

Ball on top

Roll ball with hand Requires less space than

mouse

Laptop computers

Touchpad Pressure-sensitive pad Cursor moves as you slide

your finger

Laptop computers


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Other Pointing Devices

Joystick

Short lever Handgrip Distance and speed of movement control pointer

position


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Touch Screens

Human points to a selection on the screen

Touch Screen is a video display screen that

receives input from touch of finger.

Types

Senses finger pressure

Light pen for pointing


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Touch Screens

Self-help stations

Easy to use

Where found Malls Government offices

ATM Fast food restaurants Drug stores


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Pen-based Computing

Small hand-held devices

Electronic pen (stylus) Pointer

Handwritten input

Personal Digital

Assistants (PDA)


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Optical Scanners

Optical recognition

Light beam scans input data

Most common type of source input

Document imaging converts paper documents to

electronic form

Converts scanned picture into characters OCR

Exact computer-produced replica of original


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Types of Scanners

Flatbed One sheet at a time

Scans bound documents Sheetfeed

Motorized rollers

Sheet moves across

scanning head Small, convenient size


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Types of Scanners

Handheld

Least expensive

Least accurate

Portable

Wide document causes problems


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Read barcodes which are patterns of printed barsappear on product packaging.

Barcodes identify product and provide informationabout product such a price.

BCR emits a beam of light that is reflected by the barcode image.

Light sensitive detector identifies barcode image byrecognizing bars.

BCR converts printed bars into a code the computercan understand.

Reader then feeds the data into the computer.

Bar Code Readers


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Voice Input

Speech Recognition Translating voice to text is a capability

known as speech recognition.

Speech recognition devices Input via a microphone

Voice converted to binary code

Problems Speaker-dependent Voice training


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Voice Input

Discrete work systems Understand isolated words

Pause between words Difficult for dictation

Continuous work systems Normal speaking pattern

Easy to use

Faster and easier to dictate


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Digital Cameras

Photos stored in electronic form

No film

Point and shoot

Edit


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Webcam A digital camera designed to

take digital photographs andtransmit them over the internet.

(WEB CAMERA) A video camerathat attaches to a computer typically via USB or that is builtinto a laptop or desktop screen.It is used mostly for videophoning over networks such as

Skype as well as tocontinuously monitor an activityand deliver the video to a Webserver for public or privateviewing.


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I.T.C - lecture2

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