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Computer Input and Output Device

Damascus Educational Center of Scholars ‐ Sy 2012‐2013 Grade 3

INPUT DEVICES

Input devices accept data and instructions from the user or from another computer system. The keyboard and mouse are examples of input devices.


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TYPES OF INPUT DEVICES

• Keyboard

• Mouse

• Punched cards

• Optical Character Readers (OCR)

• Barcode Reader

• Pens

• Touch Screen


The Standard Keyboard Layout

How a Keyboard Works.

KEYBOARD

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STANDARD KEYBOARD LAYOUT

• A standard computer keyboard has about 100 keys.

• Most keyboards use the QWERTY layout, named for the first six keys in the top row of letters.


VIEW THE PARTS OF THE KEYBOARD


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HOW A KEYBOARD WORKS

When you press a key:

• The keyboard controller detects the keystroke.

• The controller places a scan code in the keyboard buffer, indicating which key was pressed.

• The keyboard sends the computer an interrupt request, telling the CPU to accept the keystroke.


Keyboard Operation Layout


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WHAT IS A MOUSE?

• The mouse is a pointing device. You use it to move a graphical pointer on the screen.

• The mouse can be used to issue commands, draw, and perform other types of input tasks.


MOUSE TECHNIQUES

Using the mouse involves five techniques:

– Pointing; Move the mouse to move the on-screen pointer.

– Clicking; Press and release the left mouse button once.

– Double-clicking; Press and release the left mouse button twice.

– Dragging; Hold down the left mouse button as you move the pointer.

– Right-clicking; Press and release the right mouse button.


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VARIANTS OF THE MOUSE

• Trackballs

• Trackpads

• Integrated Pointed Devices


TRACKBALLS

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• A trackball is like a mouse turned upside-down.

• Use your thumb to move the exposed ball and your fingers to press the buttons.

Many styles of trackball are available.


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TRACKPADS

• A trackpad is a touch-sensitive pad that provides the same functionality as a mouse.

• To use a trackpad, you glide your finger across its surface.

• Trackpads provide a set of buttons that function like mouse buttons.


DEVICES FOR THE HAND

• Pens

• Touch Screens

• Game Controllers


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The user can point, tap, draw and write on the computer’s screen with a pen.

Sample of Device with Pen


Sample of Touch Screen Device


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Sample of Bar Code Readers

Bar code readers commonly track sales in retail stores


OUTPUT DEVICES

• Types of output devices

– Monitors

– PC Projectors

– The most commonly used types of printers

– Speakers


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MONITORS

CRT Monitors

Flat-Panel Monitors

Comparing Monitors

Video Controllers


PC PROJECTORS

A PC projector connects to a PC and is used to project images on a large screen.

Many PC projectors provide the same resolutions and color levels as high-quality monitors.

Digital light processing (DLP) projectors use a microchip containing tiny mirrors to produce very sharp, bright images.


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SOUND SYSTEMS

Multimedia PCs come with a sound card, speakers, and a CD-ROM or DVD drive.

A sound card translates digital signals into analog ones that drive the speakers.

With the right software, you can use your PC to edit sounds and create special sound effects.


SOUND SYSTEMS ILLUSTRATION


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TYPES OF PRINTERS

• Dot matrix

• Ink jet

• Laser


DOT MATRIX

• The paper is pressed against a drum (a rubber-coated cylinder) and is intermittently pulled forward as printing progresses.

• The electromagnetically-driven print head moves across the paper and strikes the printer ribbon situated between the paper and print head pin.

• The impact of the print head against the printer ribbon imprints ink dots on the paper which form human-readable characters.

• It is ideal for environments that frequently print on carbon copy.


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INKJET PRINTERS

• The relative low cost of the printers and multi-purpose printing abilities make it a good choice.

• Inkjets use quick-drying, water-based inks and a print head with a series of small nozzles that spray ink on the surface of the paper.

• The print head assembly is driven by a belt-fed motor that moves the print head across the paper.


LASER PRINTERS

• Laser printers are known for their high volume output and low cost-per-page.

• Laser printers share much of the same (or similar) technologies as photocopiers.

• Mechanized rollers and gears pull a sheet of paper from a paper tray and through a charge roller, which infuses the paper with an electrostatic charge. The paper then passes through a printing drum, which is itself inversely charged and scanned by a laser that emits the print contents across the drum, discharging the drum at points corresponding to text and image points.


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Thank You

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