Presentation Transcript
Slide 1:Input Output Devices
What are they good for? :What are they good for? Execute instructions
Provide access to data
Obtain results
Provide ways to communicate
System Bus :System Bus Communication 1st happens internally
Right circuit board ↔ device
Communication through parallel lines
Bus
Usually 16, 32, 64 lines
# of bits & speed affects speed of communication
Video Display Terminal :Video Display Terminal Keyboard
Allows alphanumeric characters to be entered into computer
Extra keys
Ctrl, Alt, Esc → to move cursor
Function keys (10-12) for special commands Display Monitor
High quality monitor or cathode ray tube (CRT) similar to TV
Color image comes from CRT with 3 electron guns
Red, blue, green
Energy shot determines color displayed
Mouse :Mouse Allows rapid interaction with screen information
Used for pointing and selecting information from screen
Allows direct interaction with graphics
Different Designs :Different Designs Mechanical mouse
Ball protrudes from hole in the bottom
As mouse is moved, the ball rotates and turns rollers inside
Trackball
Upside down mouse
User directly rolls ball on top of housing
Optical mouse
Light illuminates grid surface
Lens focuses image of the lines of the grid
Light is translated into signals by photocathode
Other Designs :Other Designs Joystick
Light pen
Laser mouse
Printers: Laser :Printers: Laser Rapidly turns beam of laser light on and off
Reflected onto a print drum
As the drum turns, the image is transferred to the paper
Heat and pressure from rollers bind the image to the paper
Printers: Inkjet :Printers: Inkjet Small print head with a vertical array of holes
Electric pulse flows through resistors at the bottom of each nozzle chamber
Heat from resistors heats ink
Boiling bubble then hits paper
Modem :Modem Connects PC over a phone line
Produces a continuous frequency to transmit info
speed measured in bits/second (baud)
Usually 28,800 or 56,000 baud
Useful for small files
Large files use: ISDN, DSL, T1, T3, or higher