Business Studies Stage I Computer Applications Slide 1

Output Devices

Output Devices are all part of the Hardware of a computer system

Output Devices are about seeing the results of your work!

Business Studies Stage I Computer Applications Slide 2

Some Output Devices

Video Monitor

Sound

ControllingOther Machines

Paper

Business Studies Stage I Computer Applications Slide 3

Types of Output

• Soft Copy• Hard Copy• Communications

Channel

Business Studies Stage I Computer Applications Slide 4

Screen Output – Soft Copy

• Video Monitor– Also called Video

Display Terminal (VDT)– Image exists in video

memory—VRAM– Monitor size is

measured diagonally across the screen

Business Studies Stage I Computer Applications Slide 5

• Images are made up ofdots called pixels forpicture elements

• The number of pixels determines the clarity of the picture on the screen

• More pixels = higher resolution = clearer picture

Pixels

Business Studies Stage I Computer Applications Slide 6

Color Depth (Bit Depth)• This means the amount of information

stored in each pixel about what is being shown on the monitor– Monochrome (1 bit of information per

pixel)• This can only be black or white

– Gray-scale (8 bits of information per pixel)• This can show more shades of grey

– True color (24 or 32 bits of information per pixel)

• This can realistically reproduce a photograph on the screen that looks very close to the original

Business Studies Stage I Computer Applications Slide 7

Examples of Color Depth

1-bit depth 4-bit depth

8-bit depth 16-bit depth

The greater the color depth the more colours that can be represented on the screen

Business Studies Stage I Computer Applications Slide 8

CRT (cathode ray tube)

LCD (liquid crystal display)

Classes of Monitors

Business Studies Stage I Computer Applications Slide 9

• A CRT is a television-style monitor

• Its features include:– Clear image– Quick response time– Low cost– Very popular

CRT (Cathode Ray Tube)

Business Studies Stage I Computer Applications Slide 10

Features of CRT Displays

• Display text and graphics• Monitors differ in resolution• Standards

– SVGA – 1024 x 768, 1208 x 1024 and 1600 x 1200

– XGA – has same resolutions but supports more colours

• Screen sizes vary from 15” to 21”

Business Studies Stage I Computer Applications Slide 11

• LCDs comprise flat-panel monitors• Found on watches, calculators,

digital cameras and notebook computers– Lighter weight– Crisp,clear images– Extra viewing area for same size– More expensive to buy– Consume less power

LCD (Liquid Crystal Display)

Business Studies Stage I Computer Applications Slide 12

Paper Output – Hard Copy

• A printer is a device that produces output on paper

• Most printers today can produce both text and graphics

• Two types of printers:– Impact printers– Non-impact printers

Business Studies Stage I Computer Applications Slide 13

Impact Printers

• There is some physical contact with the paper to produce the image ie physically striking the paper

• Types– Line printers– Dot matrix printers

Business Studies Stage I Computer Applications Slide 14

• Line printers– Used by mainframes for

jobs that need a large volume of printing

– Limited characters available– Print an entire line at a time– Cheap to run– Not high quality

Line Printer

Business Studies Stage I Computer Applications Slide 15

Dot Matrix Printer

• Have a printhead made up of columns of pins– The pins form characters and images

as patterns of dots produced when the pins strike the paper

– Reasonable quality text and graphics– Inexpensive to buy and run– Noisy

Business Studies Stage I Computer Applications Slide 16

Non-Impact Printers

• Laser Printers• Ink-jet printers• Bubble-jet printers

Business Studies Stage I Computer Applications Slide 17

Laser Printers

• Laser printers– Image transferred to

paper with a laser beam•Faster and more expensive

than dot-matrix•High-resolution output•Expensive to buy•Quite expensive to run

Business Studies Stage I Computer Applications Slide 18

Ink-Jet Printers

• Ink-jet– Dots of ink are sprayed onto the

paper to form the image– Reasonably high quality– Available in colour or B/W– Speed measured in pages per

minute– Reasonably priced– Expensive to run

Business Studies Stage I Computer Applications Slide 19

Plotters• Used by graphic

designers/architects– Image transferred to paper

with ink pens– Very high resolution – Excellent for scientific and

engineering applications

Business Studies Stage I Computer Applications Slide 20

Printing Terms

• Dots per inch (dpi)• Pages per minute (ppm)• Characters per second (cps)• Laser printers – 50 ppm• Ink-jet printers – 12 ppm

Business Studies Stage I Computer Applications Slide 21

Output You Can Hear

• Synthesizers can beused to generate music and sounds

• Many computershave synthesizers

• Sound cards havebuilt-in synthesizers

Business Studies Stage I Computer Applications Slide 22

• By turning bit information into movements (robots) or measurements (sensors), machines can control other machines:– Automated factory equipment– Telephone switchboards– Robot arms– Spacecraft

Machines Controlling Other Machines

Business Studies Stage I Computer Applications Slide 23

Output to a Network – Computer to Computer• Needs a

Communications channel

• The Internet and WWW• Needs a modem to

convert data for transmission across network