Understanding Computers, 12 th Edition, Enhanced Chapter 4 1 Input and Output

Understanding Computers, 12th Edition, EnhancedChapter 4

1

Chapter 4

Input and Output

Understanding Computers, 12th Edition, Enhanced 2

Overview This chapter covers:

Keyboards and pointing devices Scanners and related devices Biometric and multimedia input devices Various types of display devices Various types of printers Multimedia output devices


Input and Output Input devices convert data from the user into a form

understood by the computer.

Output devices convert the processed 0s and 1s into a form that the user can understand.

Hard copy—permanently recorded, such as on paper.

Soft copy—temporarily recorded, such as on a computer screen.


Keyboards

Computers usually use a keyboard for text-based input.

Keyboards can differ in number of keys, key arrangement, types of special keys, and touch.

Function keys enable software packages to be customized to meet a user's applications needs.

The numeric keypad makes it easy to enter numbers quickly.


Keyboards, Cont’d.

Portable keyboards and thumb pads are increasingly being used with portable PCs and mobile devices.


Pointing Devices

Mice

The mouse is the most common type of pointing device.

Can be mechanical or optical.

Used to select onscreen objects, issue commands, move objects, scroll through documents, etc.


Pointing Devices, Cont’d.

Electronic pens (light pen, stylus)

An alternative to the mouse to select objects or to write or draw on the screen.

Commonly used with: Graphics tablets Digital portfolios and digital pens Signature capture devices Pen-based computers Handwriting recognition technology



Touch screens Used when other input

devices are impractical.

Often used when consumer input is required, as in consumer kiosks.



Other common pointing devices

Joysticks and other gaming devices

Trackballs

Pointing sticks

Touch pads


Scanners and Related Devices

Source data automation involves converting source documents to digital form or initially collecting data in digital form.

Often involves scanning or reading devices.


Scanners

Scanners (optical scanners) convert hard-copy images of text pages, photographs, and drawings into digital form.

Types of scanners: Flatbed Sheet-fed Handheld Drum Three-dimensional

Quality of scanned images are measured by resolution.


Optical Mark Readers (OMRs)

Read optical marks, such as on:

Exams Census forms Voting ballots Lottery forms


Bar-Code Readers

Bar code—an optical code consisting of several bars of varying widths that form a unique, identifiable code.

Read by fixed or portable bar-code readers.

Common types: Universal Product Code (UPC) POSTNET code Proprietary codes for shippers, hospitals, and

other businesses


Optical Character Recognition (OCR) Devices

Optical characters are designed to be identifiable by humans as well as OCR device.

Widely used in turnaround documents, such as monthly bills.


Magnetic Ink Character Recognition (MICR) Readers

MICR readers can read the special magnetic characters and sort and processdocuments accordingly.

Used primarily for processing checks.


Biometric Input Devices

Used to input biometric data about a person.

Biometric data is based on unique physical characteristics (e.g. fingerprint) or personal traits (e.g. voice).

Used for access and to verify transactions.

Biometric readers can be stand-alone or built into keyboards or other hardware devices.


Multimedia Input Devices

Digital cameras record data onto digital media instead of conventional film or tape.

Images can be transferred to a PC via a cable or the storage media (such as a flash memory card with a digital still camera).

Can be digital still cameras or digital video cameras.


Multimedia Input Devices, Cont’d. Digital still cameras

Images are usually stored on flash memory cards.

Photos can usually be immediately previewed and deleted, if needed.

Photos are easily transferred to a PC to be stored and/or printed.

Camera quality is measured in mexapixels.

Digital photos can be printed at home or at a photo lab.


Multimedia Input Devices, Cont’d.

Digital video cameras

Store images on digital media (typically digital tape or optical discs).

Video can be easily transferred to a PC for editing and/or burning onto a DVD.

Can be used for videoconferencing and Web cams.


Multimedia Input Devices, Cont’d.

Audio input devices

Voice-input systems convert spoken words to digital data.

Voice input can be used to input data or commands into a PC as well as for telephony.

Music-input systems can input and record music (either original compositions or via a CD or DVD player).


Display Devices

Display device characteristics

Color vs. monochrome displays

Size (measured diagonally)

Screen resolution

Graphic standards


Display Devices, Cont’d.

CRT (cathode-ray tube) monitors—display images similar to conventional televisions.

Quality is measured in dot pitch.



Flat-panel displays—form images by manipulating electronically-charged chemicals or gases between thin panes or glass or plastic.

Common types: Liquid crystal displays (LCD) Gas plasma

Used for monitors, televisions, handheld devices, and other consumer products.




Smart displays

HDTV monitors

Data projectors

Emerging display technologies and applications (e.g. flexible displays, e-paper, integrated displays, etc.)


Printers Printer characteristics

Printer resolution—measured in dots per inch (dpi)

Impact vs. non-impact printing

Color vs. black and white

Personal vs. network printers

Speed


Laser Printers

The standard for business documents.

Work similarly to photocopy machines; print with toner powder.

Are usually black and white, though color laser printers are available.

Fast print speed; print one page at a time.


Ink-Jet Printers

Print with tiny drops of liquid ink.

Typically print in color.

Often the choice for home use.

Print fairly slowly, one line at a time.

Quality not quite as good as a laser printer.


Special Purpose Printers

Photo printers

Bar-code printers

Label printers

Portable printers

Plotters and wide-format ink-jet printers

Fax machines

Multifunction devices

3D Printers


Multimedia Output Devices

Speakers Voice-output

systems- sometimes called text-to-speech systems

Headphones and Headset

Documents

Understanding Computers, 12 th Edition, Enhanced Chapter 4 1 Input and Output