CS 3 - Kurtz  Santa Monica College 

INPUT & OUTPUT

 

 

Ink-jet Printers 

 

Spray magnetized ink onto paper
Ink cartridges are replaced when they run dry
Cartridges for black, yellow, magenta, and cyan
Color cartridges are often combined into one.
Cost is low enough for home use
Popular for inexpensive color printing

 

Dot Matrix Printers 

 

Tiny solenoids "impact" an inked ribbon against paper
The ribbon is replaced when it gets dry.
Inexpensive, rugged, and noisy
Used on multi-part forms
Low print quality

 

Laser Printers 

 

Laser writes to a light sensitive drum which transfers toner to paper
A toner cartridge is replaced when toner is expended.
Toner cartridge also contains the print drum.
Robust enough for shared office use

 

Thermal Printers 

 

Paper reacts to heat and electrical charge and changes color
Special coated paper is required
Very inexpensive
Low print quality
Images tend to fade over time

 

Cathode Ray Tube 

 

CRT
 Type of video monitor 
Similar to a television screen 
Beam of electrons is emitted by an electron gun (cathode) which illuminates phosphors on the screen, causing them to glow 
Monochrome monitors use one electron gun 
Color monitors require three electron guns, red, green, and blue (RGB) 
Monitor screens are made up of individual pixels or picture elements 
More pixels make images smaller and smoother
Typical PC Monitor resolutions: 

800 x 600 (800 pixels across and 600 pixels down) 
1024 x 768
1280 x 1024

 

Liquid Crystal Device

LCD
Uses Liquid Crystal Material sandwiched between polymer layers
LCD elements are activated by an electrical current.
Active matrix, or TFT technology is brighter, has better color, is visible at an angle, but more power is required than passive matrix LCD devices.
Passive matrix requires less power than TFT, but is visible only from front.
Generally have low power requirements and are suitable for mobile (battery) use
Take up less space than CRT monitors

 

Alphanumeric Keys 

 

Letters, numbers, and punctuation marks
"QWERTY" arrangement similar to typewriter

 

Function Keys 

 

Labeled F1, F2, etc. 
Get their meaning from the program being executed
Have no intrinsic function

 

Cursor Keys 

 

Used to move cursor on screen 
Arrow keys, PgUp, PgDn, Home, End

 

Numeric Keypad 

 

Similar to a 10-key calculator keypad

 

Special Keys 

 

NumLock, Control, Shift, Alt, Esc, Insert, Del, Enter, Backspace

Scanners

Capture an image of a document directly
Resolution in dots per inch (dps)

Optical Character Recognition

OCR
Used to convert scanned document images into a native format such as Word, Excel, etc.

Optical Mark Recognition

OMR
Scans for marks on a form such as a Scan-tron

Magnetic Ink Character Recognition

MICR
Recognizes Magnetic Ink in shape of special characters
Used primarily in banking industry

Bar Codes

Optically scanned
Used in retail (grocery, pharmacy, hardware, stationary, etc.),
Vehicles, mail, books, etc.

Plotters and Large Format Printers

Used in engineering, drafting, and graphic arts
Large Format Printer
Electrostatic Plotter
Pen Plotter
Used for large printed output

Audio Output

Speakers & Headsets
 

Television

Can be a good output device
Analog televisions usually require a converter
Digital Television (DTV) is generally superior to analog television
High Definition Television (HDTV) is an advanced form of DTV