Chapter 6: Input & Output Taking Charge of Computing & Communications

Key Questions 6.1 How is input and output hardware used by a computer system? 6.2 What are the three categories of input hardware, what devices do they include, and what are their features? 6.3 What are the two categories of output hardware, what devices do they include, and what are their features? 6.4 What are some examples of the future of input and output technology?

I. Input Hardware n Keyboards n Pointing Devices n Source Data-Entry Devices

II.Pointing Devices n Mice, Trackballs, & Joysticks –Mouse –Trackball –Pointing stick –Touchpad n Light Pen n Digitizing Tablet n Pen-Based Systems

III. Common Hardware for Source Data-Entry n Bar-Code Readers –Bar codes(Universal Product Code or UPC) n Mark-Recognition & Character-Recognition –Magnetic-ink char recognition (MICR) Banking industry –Optical-mark recognition (OMR) Tests and examinations –Optical-char recognition (OCR) Utility companies using turn-around documents Convert printed text to digital form

Checks use magnetized ink that can be read by a bank’s magnetic- ink character-recognition equipment. MICR technology

Other Input Devices n Scanning Devices: Imaging Systems –Flatbed image scanners –Sheetfed image scanners –Handheld image scanners n Audio-Input n Video-Input n Digital Cameras

Summary of input devices

IV.Output Hardware n Softcopy –data that is shown on a display screen or is in audio or voice form n Hardcopy –Printed on paper, microfilm and microfiche

V. Softcopy: Display Screens n Cathode-Ray Tubes (CRTs) n Flat-Panel Displays –Substances between plates Liquid crystal display (LCD) Electroluminescent (EL) Gas-plasma display –Arrangements of transistors.Active-matrix:brighter, sharper and $$$.Passive-matrix: need less power

How a CRT works

Display Screen Screen Clarity –Resolution: image sharpness horizontal & vertical pixels: 800x600, 1024x768 –Dot pitch: space between adjacent pixels dot pitch <.31 millimeter provide clear images –Refresh rate: how often the pixels are recharged n Monochrome Versus Color Screens n Bitmapped Displays n Video Display Adapters

VI.Hardcopy Output n Impact Printers –Print char or images by striking a mechanism (hammer) against an inked ribbon, leaving an image on paper –Dot Matrix Printer n Nonimpact Printers –Laser printer –Ink-jet printer –Thermal printer

*cps = characters per second; ppm = pages per minute Printer comparisons

In & Out n Terminals: –Used to access another machine –Monitor & Keyboard –Dumb: no local processing power –Intelligent: CPU and RAM –Special Purpose: Point-of-sale (POS) n Touch Screens

Summary of output devices