IT_Chapter_

Monitors

• Most common output device

• Connects to the video card

• Categorized by color output

– Monochrome

• One color with black background

– Grayscale

• Varying degrees of gray

– Color

• Display 4 to 16 million colors

• Cathode Ray Tube (CRT)

– Most common type of monitor

– Electrons fired from the back

– Electrons excite phosphor to glow

– Phosphor is arranged in dots called pixels

– Dot mask ensures proper pixel is lit

• CRT color

– Phosphor dots arranged in triads

– Red, green, and blue dots

– Three colors blend to make colors

– Varying the intensity creates new colors

• CRT drawbacks

– Very large

– Very heavy

– Use a lot of electricity

• Liquid Crystal Display (LCD)

– Commonly found on laptops

– Desktop versions exist

– Solve the problems of CRT

– Fluorescent lights provide illumination

• Drawbacks to LCD

– More expensive than CRT

– Must sit directly in front of screen

– Can be more fragile than CRT

• Size of monitor

– Measured in inches

– Measured diagonally

– Actual size

• Distance from corner to corner

– Viewable size

• Useable portion of the screen

• Resolution

– Number of pixels on the screen

– Higher number creates sharper images

– Higher number creates smaller images

• Refresh rate

– Number of time the screen is redrawn

– Modern equipment sets this automatically

– Improper settings can cause eyestrain

Monitors and Video Cards

• Dot pitch

– Distance between the same color dots

– Ranges between .15 mm and .40 mm

– Smaller creates a finer picture

– Should be less than .22

Video Cards

• Device between the CPU and monitor

• Better cards result in better output

• Removes burden of drawing from CPU

• Have their own processor and RAM

• Modern cards have up to 512 MB RAM

• Capable of rendering 3D images

Sound Systems

• Integral part of the computer experience

• Capable of recording and playback

• Sound card

– Device between the CPU and speakers

– Converts digital sounds to analog

– Can be connected to several devices

– Modern cards support Dolby Surround Sound

• Headphones and headsets

– Replacement for speakers and microphones

– Offer privacy

– Does not annoy other people

– Outside noise is not a factor

– Headsets have speakers and a microphone