Input and Output Computer Devices

Pengantar Teknologi Informasi

What Is Input?

What is input?

Input device is any hardware component used to enter data or instructions

Data or instructions entered into memory of computer

What Is Input?

What are the two types of input?

Unprocessed text, numbers, images, audio, and video

Instructions Programs Commands User responses

Data

The Keyboard

How is the keyboard divided? Typing area Numeric keypad Function keys, special

keys that issue commands

The Keyboard

What are alternative forms for commands?

MICROSOFT WORD KEY COMBINATION EQUIVALENTS

Key Menu |Command Combination Command Button

Copy Shift+F2 or Edit | CopyCtrl+C

Open Ctrl+F12 File | Open

Paste Ctrl+V Edit | Paste

Many programs allow you to use key combination, menu, or button to obtain same result

Pointing Devices

What is a mouse? Pointing device that fits under palm of hand

Pointing device controls movement of pointer, also called mouse pointer

Mechanical mouse has rubber or metal ball on underside

mouse buttonswheel button

mouse pad

ball

Pointing Devices

What is an optical mouse? No moving mechanical

parts inside Senses light to detect

mouse’s movement More precise than

mechanical mouse Connects using a

cable, or wireless

Voice Input

How does voice recognition work?Step 2. An analog-to-digital converter (ADC) translates sound waves into digital measurements computer can process. Measurements include pitch, volume, silences, and phonemes. Phonemes are sound units such as aw and guh.

10010111010110101100001101

Step 3. Software compares spoken measurements with those in its database to find a match or list of possible matches.

Matches

Step 4. To narrow a list down, software presents user with a list of choices or uses a natural language component to predict most likely match. User may correct any selection made by software.

Natural Language Engine

Step 1. A user dictates text into a microphone.

Digital Cameras

What is a digital camera? Allows you to take

digital pictures Images viewable

immediately on camera Download to

computer Post pictures

to Web

Digital Cameras

How does a digital camera work? Step 1. Point to the image to photograph and take picture. Light passes into the lens of the camera.

Step 2. Image is focused on a chip called a charge-coupled device (CCD).

Step 3. CCD generates an analog signal that represents the image.

Step 4. Analog signal is converted to digital signal by analog-to-digital converter (ADC).

Step 5. Digital signal processor (DSP) adjusts quality of image and usually stores digital image on miniature mobile storage media in the camera.

Step 6. Images are transferred to a computer’s hard disk by plugging one end of the cable into a camera and the other end into a computer; or images are copied to hard disk from storage media used in the camera.

Step 7. Using software supplied with the camera, images are viewed on screen, incorporated into documents, edited, and printed.

Digital Cameras

What is resolution? Sharpness and clarity of image The higher the resolution, the better the image

quality, but the more expensive the camera Pixel (picture element)

is single point in electronic image Greater the number of

pixels, the better the image quality

Video Input

What is video input? Process of entering full-motion images

into computer Video capture card is

adapter card that converts analog video signal into digital signal that computer can use

Digital video (DV) camera records video as digital signals

Video Input

What are a PC video camera and a Web cam? PC video camerac—cDV camera used to capture video

and still images, and to make video telephone calls on Internet Also called PC camera

Web camc—cvideo camera whose output displays on a Web page

What is Output?

What is output? Data that has been processed into a useful form,

called information Output device is any hardware component that can convey

information to user

Display Devices

What is a display device? Output device that

visually conveys information Information on display

device sometimes called soft copy

Monitor houses display device as separate peripheral

CRT Monitor

What is a CRT monitor? Contains cathode-ray

tube (CRT) Screen coated with tiny

dots of phosphor material Each dot consists of a red,

blue, and green phosphor Common sizes are 15, 17,

19, 21, and 22 inches Viewable size is diagonal

measurement of actual viewing area

CRT Monitor

What is the ENERGY STAR program? Encourages manufacturers to create energy-efficient

devices that require little power when not in use Monitors and devices meeting guidelines display

ENERGY STAR label

CRT Monitor

What is resolution? Sharpness and clarity of image

Refresh rate is speed at which monitor redrawsimages on screen

Higher resolution makes image sharper, displays more text on screen, makes some elements smaller

CRT Monitor

How does video travel from the processor to a CRT monitor?

Step 1. The processor sends digital video data to the video card.

Step 2. The video card’s digital-to-analog converter (DAC) converts the digital video data to an analog signal.

Step 3. The analog signal is sent through a cable to the CRT monitor.

Step 4. The CRT monitor separates the analog signal into red, green, and blue signals.

Step 5. Electron guns fire the three color signals to the front of the CRT.

Step 6. An image is displayed on the screen when the electrons hit phosphor dots on the back of the screen.

Video card (also called a graphics card) converts digital output from computer into analog video signal

CRT Monitor

What are video standards? Video Electronics Standards Association (VESA)

develops video standards

CRT Monitor

What are various video card configurations?

Flat-Panel Displays

What is a flat panel display? Uses liquid crystal display

Also called LCD monitor Takes up less desk space

than CRT monitor Consumes less than

one-third the power

Flat-Panel Displays

How does LCD work?

Step 1. Panel of fluorescent tubes emits light waves through polarizing glass filter, which guides light toward layer of liquid crystal cells.

Step 2. As light passes through liquid crystal, electrical charge causes some of the cells to twist, making light waves bend as they pass through color filter.

Step 3. When light reaches second polarizing glass filter, light is allowed to pass through any cells that line up at the first polarizing glass filter. Absence and presence of colored light cause image to display on the screen.

Liquid crystal cells

Color filter

Transparent electrodes

Alignment layer

Polarizing glass filter

Fluorescent tube panel

Uses liquid compound to present information on a display

Flat-Panel Displays

How do you use an LCD monitor with a video card? Plug monitor into Digital Video Interface (DVI) port

on computer

standard monitorport S-video port

DVI port

Flat-Panel Displays

What is a gas plasma monitor? Displays image by applying voltage to layer of gas

Larger screen size and higher display quality than LCD, but much more expensive

Video conferencePlay gamesShop

HDTV HDTV (high-definition television)(high-definition television)

works directly with interactive TV

Flat-Panel Displays

What is interactive TV?

Two-way communications technology in which users interact

with television programming

BankVote or respond to

network questionnairesSelect a movie from a

central library of movies

SpeedSpeedSpeedSpeed

Printers

How do you know which printer to buy?

BudgetBudgetBudgetBudget Color orColor orblack and whiteblack and white

Color orColor orblack and whiteblack and white

Cost per pageCost per pageCost per pageCost per page Paper typesPaper typesand sizesand sizes

Paper typesPaper typesand sizesand sizesPhoto printingPhoto printingPhoto printingPhoto printingGraphicsGraphics

capabilitycapabilityGraphicsGraphicscapabilitycapability

SystemSystemcompatibilitycompatibility

SystemSystemcompatibilitycompatibility

Depends on printing needs

WirelessWirelesscapabilitycapabilityWirelessWireless

capabilitycapabilityFuture needsFuture needsFuture needsFuture needs

Speakers and Headsets

What is an audio output device? Computer component that produces music, speech, or

other sounds Speakers and headsets are common devices