Lesson 2

CT Intro

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Input and Output Devices

Input devices data entered into the computer through a variety of devices such as keyboards, microphone, scanner, flash drive or mouse.

Output devices allows a user to view or listen to the data a computer processes such as a monitor, printer, headphones, or speakers.

Some devices can perform both input and output operations. (Modems)

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Input Devices – The Keyboard

The keyboard is the most common input device. As you press keys on the keyboard, an electrical signal

representing that key is sent to the computer. Keyboards are divided into sections:

Typewriter keys: The standard alphabetic and numeric characters you would find on a typewriter.

Function keys: Special keys that perform some specific function for the application being run.

Numeric keypad: Used for mathematical operations. Directional keys: Used to move the cursor around the

screen.

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Standard Input Devices-Keyboard

Most commonly used input device. Besides a traditional keyboard, popular types include:

– Ergonomic– Cordless or

wireless– Specialized

– Security– Foldable or

flexible– Laser virtual

keyboard

Security Keyboard

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Foldable Keyboard

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Laser Virtual Keyboard

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Ergonomic Keyboard

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Input Devices – The Mouse

The mouse is a pointing device that rolls around on a flat surface and controls the location of the pointer on the screen.

The mouse performs the following functions: Pointing: Place the on-screen pointer at a specific place. Clicking: Press and release the mouse button. Dragging: Holding down the mouse button and

dragging an object to a new location by dragging the mouse.

Double-clicking: Pressing and releasing the mouse button twice very quickly.

Right-clicking: Pressing the right mouse button.

Mouse: Most commonly used pointing

device. Types include:

Standard Input Devices (continued)

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– Mechanical– Optomechanical– Optical– Wireless

Optical mouse

Wireless Mouse and Receiver

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Other Input Pointing Devices

In addition to the mouse, there are other devices that control the on-screen pointer, including a Joystick: Joysticks consist of a metal or plastic handle

mounted on a base that you can move in any direction to move the pointer or other object.

These are typically used for video games. They frequently have buttons that can be pushed

or clicked to control input/output. Trackball: A pointing device that works like a mouse

turned upside down; the ball is on top, operated by your thumb and fingers.

These are frequently found on notebook computers.

Trackball and Joystick

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Trackball Joystick

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Other Input Devices (Part I)

A graphic tablet is a flat drawing surface connected to the computer. The user draws on the surface, and the figures or

writing on the tablet can be input to the computer for processing.

Touch display screens contain pictures or shapes that the user can press to input that information.

Voice recognition devices allow a user to speak to a computer and have their words input to an application program. These usually require a microphone and special

voice recognition software to be installed on the computer.

Graphics Tablet and Touch Display Screen

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Graphics Tablet Touch Display Screen

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Other Input Devices (Part II)

Scanners are devices that can convert a graphical image into a digital image and input it to the computer. Types of scanners include

Image scanners for scanning images and text. Bar code scanners to read product bar codes. Magnetic scanners to read the magnetic strip on a

credit card. Optical Character Reader (OCR) scanners read

answers on a scantron answer sheet. Video input from a camcorder or VCR can be input

using video capture cards. Digital cameras takes pictures are stored digitally and

then transferred to the computer’s memory. Their images can be input directly into the computer.

Scanners

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Image Scanner

Bar Code Scanner

Magnetic

Scanner

Scanner and Digital Camera

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Optical Character Reader Scanner

Digital Camera

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Standard Input Devices (continued)

Touchpad: Common feature on laptops; a

specialized surface that converts the motion and position of your fingers to a position on the screen.

Pointing Stick: A pressure-sensitive device located on

the keyboard of many notebook computers and moved with the forefinger.

Touchpad and Pointing Stick

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Touch Pad Pointing Stick

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Standard Input Devices (continued)

Stylus: Pen-like writing instruments to input

information to a PDA or other mobile device.

Environmental Probes and Sensors:

Used with a Web browser to monitor elements of the work area such as humidity, pollution, or security

Stylus

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Remote Controls: An input device used for televisions,

lights, and fans as well as for industry and business applications.

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Specialized Input Devices (continued)

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Specialized Input Devices (continued)

Security Devices: Biometric devices consist of a reader or scanning device and software that

converts the scanned information into a digital format. The way biometric technology works:

Enrollment: User establishes baseline measurement Submission: User presents proof of identity Verification: System compares samples

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Fingerprint Scanner

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Specialized Input Devices (continued)

Virtual Devices: Use the synchronized positioning of light-

emitting and sensing devices to detect user input; for example, a virtual computer keyboard.

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Output Devices - Monitors

Monitors are used to display video output to a user. Monitors may be monochromatic or color.

Monochromatic monitors display output in a single-color display.

Factors that influence the quality of a monitor are Screen size: The diagonal measurement in inches

of the display area. Resolution: The number of pixels that can be

displayed in the display area. Dot pitch: The distance between each pixel in the

display area.

Cathode Ray Tube (CRT) Monitor

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Liquid Crystal Display (LCD) Monitor

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Gas Plasma Display Monitor

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Output Devices - Printers

Printers are used to create a hard copy of a document or image. Printers vary by speed, quality, and price.

The most popular types of printers are Laser: Produce images using the same techniques

as copier machines. Ink-Jet: These use fine nozzles to spray ink onto

the page as the paper passes through. Dot matrix: These work similarly to a typewriter in

that ink is transferred to the paper by some part of the printer striking a ribbon to transfer an image.

Laser Printer

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Inkjet Printer

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Dot Matrix Printer

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Specialized Output Devices (continued)

Specialized Printers: Line printer: High-speed printer attached primarily to large computers. Thermal: Forms characters by heating paper. Mobile: Small, battery-powered printer. Label and postage: Prints labels, including postage, on adhesive-type paper. Plotters are printers that use pens to draw lines to create maps, charts, and blueprints. used by engineers, architects, and artists.

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Plotter

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Other Output Devices

Multifunction printer: Combines various output options such as printing, scanning, and copying.

Projectors are used to project a large image of what is on the computer screen.

Speakers allow you to hear recorded music or speech from your computer.

Multifunction Printer, Projector, and Speaker

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Multifunction Printer

Projector Speaker

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Specialized Output Devices

Fax machines and fax modems: Transmit and receive documents through phone lines or computer.

Control devices/robots: Robotics is the study, design, and use of robot systems for manufacturing.

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Fax Machine

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Specialized Output Devices (continued)

Output Devices for the Physically Challenged: Various special devices are available:

Screen magnifiers: Enlarge information on the computer screen. Screen readers: Use speech synthesizers to read content for people who are blind or visually impaired. Voice synthesizers: A voice changes written computer text into synthetic speech.

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Connecting Input and Output Devices to the Computer

Ports and Connectors: A port, or jack, is an

interface to which a peripheral device attaches to or communicates with the system unit.

Besides traditional, FireWire, and USB ports, special-purpose ports include SCSI, IrDA, and Bluetooth.

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Ports

Serial Ports – transmits data one bit at a time. Example (Mouse)

Parallel Port – transmits eight bits at a time (Printer)

Universal Serial Bus (USB) – Standard for computer ports that support data transfer rates up to 200 million bits per second. Can connect up to 127 devices at one time. Has replaced serial and parallel ports on

newer computers

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Ports

USB Supports Plug-and-play refers to the

ability of a computer system to configure expansion boards and other devices automatically.

Supports Hot Plugging is the ability to add and remove devices to a computer while the computer is running and have the operating system automatically recognize the change.

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Ports

FireWire Also known as IEEE and IEEE 1394B. Supports data transfer rates up to 400

mbps and can connect up to 63 external devices.

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Special-Purpose Ports

Small Computer System Interface (SCSI) Standard Interface for connection

peripherals such as disk drives and printers.

IrDA Wireless port that allows data to be

shared between devices using infrared light.

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Special-Purpose Ports

Bluetooth Uses radio waves and provides wireless

short-range communications between both mobile and stationary devices.

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Connecting Input and Output Devices to the Computer (continued)

Hardware Installation: For most hardware devices to work, they need a set of instructions that communicates with the

computer’s operating system, called a driver. If the operating system already contains the driver, it performs an automatic plug-and-play installation

for newly connected devices.

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Computer Performance Factors

A variety of factors affect a computer’s performance: Microprocessor: The higher the generation,

the faster and better the processing speed. Random access memory (RAM): Helps

increase the processing cycle and enhance performance.

Hard disk: Bigger and faster process data faster.

Video: Can enhance or slow down performance.

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