Chapter 5

Input Users submit input dataOutput Users get processed information

Data from the user to the computer

Converts raw data into electronic form

Traditional◦ Looks like typewriter

with extra keys Non-traditional

◦ Fast food restaurants◦ Each key represents a

food item rather than a character

Function Keys Give commands Software specific

Main Keyboard Typewriter keys Special command

keys

Numeric KeysNum Lock – toggle On – numeric data & math symbolsOff – cursor movement

Cursor Movement Keys

Enter

Esc

Alt

Ctrl

Caps Lock

Shortcut

Windows

Shift

Position a pointer / cursor on the screen

Controls drawing instruments in graphics applications

Communicate commands to a program

Types◦ Mechanical◦ Optical◦ Wireless

Features◦ Palm-sized◦ 1 or 2 buttons◦ Wheel

TrackballUpside-down mouseBall on topRoll ball with handLaptop computers

TouchpadPressure-sensitive padCursor moves as you

slide your fingerLaptop computers

Pointing stick Pressure-sensitive post Mounted between G and H keys on keyboard Apply pressure in a direction to move cursor

Joystick Short lever Handgrip Distance and speed of movement control

pointer position

Digitizing tablet Rectangular board Invisible grid of electronic dots Write with stylus or puck Sends locations of electronic dots as stylus

moves over them Creates precise drawings Architects and engineers

Human points to a selection on the screen

Types◦ Edges emit horizontal and vertical beams of

light that crisscross the screen◦ Senses finger pressure◦ Light pen for pointing

Kiosks◦ Self-help stations◦ Easy to use

◦ Where found Malls Disney World Government offices

Small hand-held devices

Electronic pen (stylus)◦ Pointer◦ Handwritten input

Personal Digital Assistants (PDA)

Special equipment to collect data at the source

Sent directly to a computer Avoids need to key data Related input areas

◦ Magnetic-Ink Character Recognition◦ Scanners◦ Optical recognition devices◦ Voice

Read characters made of magnetic particles

Numbers on the bottom of checks

MICR inscriber – adds characters to check that show amount cashed

Optical recognition Light beam scans input data Most common type of source input Document imaging – converts paper

documents to electronic form Converts snapshots into images Converts scanned picture into characters –

OCR

Exact computer-produced replica of originalExact computer-produced replica of original

Flatbed◦ One sheet at a time◦ Scans bound documents

Sheetfeed◦ Motorized rollers◦ Sheet moves across scanning

head◦ Small, convenient size◦ Less versatile than flatbed◦ Prone to errors

Handheld◦ Least expensive◦ Least accurate◦ Portable◦ User must move the scanner in a straight line at a

fixed rate◦ Wide document causes problems

Photoelectric device Reads bar codes Inexpensive Reliable Where Used?

◦ Supermarket – UPC◦ Federal Express

Speech Recognition Speech recognition

devices◦ Input via a microphone◦ Voice converted to binary code

Problems◦ Speaker-dependent◦ Voice training

Changing radio frequencies in airplane cockpits

Placing a call on a car phone Requesting stock-market quotations

over the phone Command from physically disabled

users

Information for the user Types

◦ Screen – soft copy◦ Printer – hard copy◦ Voice◦ Sound◦ Graphics

Data that is entered appears on the screen

Screen is part of the monitor

Cathode Ray Tube (CRT)

Flat panel displayLiquid Crystal Display (LCD)

Raster scanning Sweeping electron beams across the back

of the screen Phosphorous coating on back Glows when hit by a beam of electrons Phosphorous loses glow and image fades

and flickers Image must be continually refreshed

Refresh rate / scan rate Number of times electron beams refreshes

the screen 80-100 times per second adequate for

clear screen image Process also used for television

Color vs. Monochrome Color

◦ Typical monitor sold today Monochrome

◦ Green or amber on a contrasting background◦ Less expensive than color

Size Measured diagonally Typical sizes

◦ Office user: 15-17 inch◦ High-powered graphics user: 19 inch◦ High-end monitors: 21 inches and up

Larger size◦ More expensive◦ More space on desktop◦ Reduces eye strain

Liquid Crystal Display (LCD)

Primarily on laptops Moving to desktop Skinny (depth)

regardless of size

Crisp, brilliant images Easy on eyes No flicker Full dimension is useable More expensive that CRT monitors

Active Matrix◦ Thin-film transistor technology (TFT)◦ Transistors for each pixel◦ Brighter image◦ Viewable from an angle

Passive Matrix◦ Fewer transistors◦ Cheaper◦ Less power

Produces information on paper Orientation

◦ Portrait◦ Landscape

Methods of printing◦ Impact◦ Nonimpact

Line printer

One line at a timeHigh volumeLow quality

Dot-matrix printer

One character at a time

Transfers images to paper using a light beam

Prints one page at a time 600-1200 dpi – High quality Speed

◦ Personal laser printers: 8-10 ppm◦ Network laser printers: 35-50 ppm◦ High-volume laser printers: up to 1000 ppm

Black and white / color

Spray ink at paper Black and white / color Low cost Need high quality paper Slower than laser

Creates multimedia outputMultiple sight and sound effects

SpeakersSound card

Enables machines to talk to people Types

◦ Voice synthesizers◦ Voice output devices◦ Audio-response units

Convert data in storage to vocalized sounds Synthesis by analysis – human sounds are

stored and reproduced as needed Synthesis by rule – creates artificial speech

Uses Automobiles Telephone surveys Catalog order is ready Your payment is late reminder

Business Education Science Sports Computer art Entertainment

Types◦ Maps◦ Charts

Help◦ Compare data◦ Spot trends◦ Make decisions quickly

Attention-getting Updated instantaneously Rendered quickly

Animated graphics Prepared one frame

at a time Examples

◦ Cartoons◦ Commercials without

humans◦ Television network’s

logo◦ Arcade games