Input and Output

Ch 5 Input and Output

Competencies

Describe input.

Describe keyboard entry, pointing devices, and scanning devices.

Discuss image capture, digitizing, and audio input devices.

Discuss output.

Describe monitors, printers, and audio output.

Discuss combination input and output devices.

Introduction

• Computer input and output devices are essentially translators.
• Input devices translate numbers, letters and actions that people understand into a form that the computer can process.
• Output devices translate the machine language the computer can process back into letters, numbers, sounds, and images that people can understand.
• Competent end users need to know about the most common input devices such as keyboards, mice, scanners, digital cameras, digitizing tablets, voice recognition devices, and MIDI.
• They also need to know about the most common output devices such as monitors, printers, and audio output.
• They also need to know about combination input/output devices such as fax machines, Internet telephones, and terminals.

What is Input?

• Input is any data or instructions that are used by a computer.
• They can come directly from you or from other sources in the form of text, numbers, pictures, voice.
• Input devices are hardware used to translate words, sounds, images, and actions that people understand into a form that the computer can process.

Keyboard Entry

• Keyboards convert numbers, letters, and special characters into electronic signals.
• Traditional, ergonomic, flexible and folding are types of keyboards.

 

Keyboards

• Traditional keyboards: full-sized, rigid, rectangular keyboards that include function, navigational, and numeric keys.
• Flexible keyboards: fold or roll up for easy packing and storage for mobile users.
• Ergonomic keyboards: similar to traditional, but designed to specifically alleviate wrist strain associated with repetitive movements of typing.
• Wireless keyboards: more expensive than traditional keyboards, but give the flexibility of un-tethering the cord.
• PDA keyboards: miniature keyboards for PDAs for sending email, etc.

Features

• Numeric keypads: easier entry of numbers and arithmetic symbols
• Toggle keys: turn a feature ON and OFF like Caps / Num Lock keys.
• Combination keys: perform action when held down in combination with 

      another key like Shift / Ctrl keys.

• Escape key: cancels a selection or a procedure.
• Function keys: shortcut for particular tasks, example F1 displays online Help.
• Navigation keys: controls the movement of cursor on the screen.

Pointing Devices

Mouse

• A mouse controls the pointer displayed on the monitor
• The mouse pointer usually appears in the shape of an arrow.
• The mouse shape can change depending on the application and status of the application.
• A mouse can have one, two, or more buttons used to select command option.
• The three basic types of mouse designs are:
• Mechanical mouse: traditional mouse with a rotating ball in the bottom and cord connecting it to the system unit. The movement of the mouse causes the roller ball to rotate and that moves the pointer on the screen.
• Optical mouse: Have no moving parts – it emits and senses light to detect mouse movement. Optical mouse is better than mechanical mouse as it can be used on any surface, is more precise, and does not require periodic cleaning.
• Cordless or wireless mouse: a battery operated device that typically uses radio waves or infrared light waves to communicate with the system. This mouse does not use any cords.
• Other devices similar to mouse include:
• Trackball (aka Roller Ball) – controls the pointer movement by rotating the ball with your thumb.
• Touch surfaces (aka Touch Pads) – controls the pointer movement by moving and tapping your fingers on the surface of a pad.
• Pointing stick (aka Track Point) – controls the pointer movement by directing the stick with your finger.

Joystick

• Most popular input device for computer games used to control game actions by varying the pressure, speed, and direction of the joystick.

Touch Screen

• A kind of monitor screen with a touch sensitive plastic screen behind which are crisscrossed invisible beams of infrared light.
• Commands or actions are selected by touching the screen with finger.
• Typically used for restaurants, ATMs and information centers

Light Pen

• A light sensitive pen-like device placed against the monitor causing it to close a photo electric circuit and identifies the spot for entering the data.
• Typically used for editing digital images.

Stylus

• A pen-like device that uses pressure to draw images on a screen
• Typically used with Tablet PCs and PDAs.
• Handwriting recognition software translates handwritten notes into a form the computer can use.
• Graphics tablets use a special graphics surface or tablet and a stylus, typically used by artists, mapmakers, and/or engineers for electronic drawings.

Scanning Devices

• Scanning devices convert scanned text and images into a form that the system unit can process.
• Scanners can read data from written document, a price tag, an image or a photograph.

Optical Scanners

• An optical scanner (aka scanner) accepts documents consisting of text and/or images and converts them to machine readable form.
• They work by recognizing light, dark, and colored areas that make up individual letters or images.
• Two basic types of scanners are:
• Flatbed scanner: works like a copy machine where the image to be scanned is kept on the glass surface.
• Portable scanner: often is a hand held device that slides across the document being scanned, making direct contact
• Typical use is by advertising professionals who scan images and combine them with text.

Bar Code Readers

• Bar code readers/scanners contain photoelectric cells that read bar codes – vertical zebra-striped marks printed on product containers.
• Typical uses are in grocery stores that use Universal Product Codes (UPC) which match up the product with a database entry containing product information such as price.
• These devices are either handheld wand readers or platform scanners.

Character and Mark Recognition Devices

• These devices read special characters and marks.
• Three types include:
• Magnetic Ink Character Recognition (MICR): used by banks for reading numbers at bottom of checks.  Special reader/sorter machines reads characters made of ink containing magnetized particles.
• Optical Character Recognition (OCR): use special pre-printed characters that can be read by a light source, and changed into machine-readable code.  Retail stores frequently used these types of scanners.
• Optical Mark Recognition (OMR) aka Mark Sensing: senses the presence or absence of a mark, such as pencil mark. It is frequently used to score multiple choice tests marked by pencil on a form.

Image Capturing Devices

• Optical scanners make a digital copy of a photograph. Image capturing devices create or capture original images.

Digital Camera

• Similar to traditional cameras except that images are recorded in digital format on a disk or in camera’s memory rather than on a film.
• One can take a picture, view it immediately and even edit it and put it on your web page immediately.

Digital Video Camera

• Unlike traditional video cameras, digital video cameras record motion in digital format on a disk or in camera’s memory.
• WebCams (Web Cameras) are inexpensive digital (video) cameras that are used for video conferencing.

Digitizing Devices

• Digitizing devices convert a sketch or figure into a form that can be processed by a computer.
• These devices have some type of flat surface and a writing device. The movements of the writing device across the surface are recorded as a series of points by the digitizing device and sent to the computer.

Graphics tablets

• Use a special graphics surface or tablet and a special stylus or penlike device.
• User either directly sketches on the tablet or traces images placed on the tablet.
• Used by artists for creating illustrations, by mapmakers to record or trace maps, by engineers to save mechanical drawings.

Digital notebooks

• Use a regular notepad kept on top of an electronic pad or tablet.
• Using a regular pen the user takes notes and creates drawings on the notepad and the below electronic pad records the movements.

 

Audio Input Devices

• Converts sound into a form that can be processed by a computer.
• The most widely used input-output device is the microphone.

Voice Recognition Systems

• Voice Recognition Systems use a microphone, sound card, and a special software allowing user to create documents using voice commands.
• Many applications now support voice recognitions systems used by doctors, lawyers and others to record dictation.
• Using a “language bar” you can switch between “voice command mode” – allowing you to control menu options, and “dictation mode” – allowing you to enter content text into a document.
• Two types of Voice Recognition Systems are:
• Discrete-speech recognition systems

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What is Output?

• Output is processed data or information
• Typically takes the form of text, graphics, photos, audio, video or images.
• Output devices are any hardware used to provide or create output for the people by translating what the computer has processed into a form that people can understand and use, for example monitors, printers, speakers, etc.
• For example, when you create a presentation you usually include text and graphics and also include photographs and even ass voice narration making it a complete presentation.
• Images displayed on monitor are often referred to as softcopy.

Monitors

• Monitor is the most frequently used output device and is also known as display screens or screens
• Two important characteristics of monitors are: size and clarity.
• Size: indicated by the diagonal length of its viewing area, common sizes are 15, 17, 19, 21 inches, for viewing more information a large monitor is needed but it is expensive.
• Resolution: clarity of monitor is indicated by its resolution, measured in pixels – dots or picture elements that form images on a monitor, e.g. a 1,280 x 1,024 resolution screen displays 1,310,720 pixels, the greater the number of pixels, the better the resolution, the greater the resolution (more pixels) the better the clarity of the image.

 

• Dot Pitch: the distance between pixels, typically measured in millimeters.  Most monitors have a dot pitch less than 0.3 mm.  The smaller the dot pitch, the better the clarity.
• Refresh Rate: how often the image is “re-drawn” on the monitor.  Most monitors have a refresh rate of 75 Hz or better (image refreshes 75 times every second).  The faster the rate, the better the image

STANDARDS

• Standards indicate monitor’s resolution capabilities. The four most common standards today are:
• SVGA (Super Video Graphics Array) – has a minimum resolution of 800 X 600 pixels. It was most popular few years back but now it is mostly used with 15-inch monitors.
• XGA (Extended Graphics Array) – has a resolution of up to 1024 X 768 pixels. A popular standard today with 17- and 19-inch monitors.
• SXGA (Super Extended Graphics Array) – has a resolution of 1280 X 1024 pixels. A popular standard today with 19- and 21-inch monitors.
• UXGA (Ultra Extended Graphics Array) – newest and highest standard used primarily for high-end engineering design and graphics art. It will be used widely when 21-inch monitors becomes common in future.

Cathode-Ray Tube (CRT)

• Most common type of monitor for office and home placed directly on system unit or desktop.
• Similar in size and technology as standard TV screens
• Advantage is they are relatively of low cost and have a high quality image display.
• Disadvantage is they take up a lot of space.

Flat-Panel Monitor or Liquid crystal display (LCD) monitors

• They use liquid crystals.
• They are portable and take up less space (thinner) and require less power than CRTs.
• They are used both for portable computers like tablet PC, handheld computers and desktop computers.
• Two basic types are:
• Passive matrix (dual scan monitors): create images by scanning the entire screen. It requires low power, but images are of poor clarity
• Active matrix (TFT: Thin Film Transistor): They do not scan the screen instead each pixel is independently activated. It is more expensive, uses more power, but produces a much better image with more colors.

Other Monitors

• E-books (aka e-book readers) are hand held, book-sized devices that display text and graphics. Using content downloaded from the Web, these devices are used to read newspapers, magazines, and entire books. The time and cost of creating and distributing e-book content is less than publishing and delivering traditional print media.
• Data projectors: are similar to slide projectors that connect to microcomputer and project the output onto a screen for a large audience. Marketing people, teachers frequently use presentation graphics programs like PowerPoint to create presentations and then deliver the presentation in classrooms or boardrooms using data projectors.
• High Definition TeleVision (HDTV): a merger of microcomputers and television (PC/TV) offers much clearer and more detailed wide screen pictures than a standard TV (but currently at more cost).  Since images are digital, they can be stored and edited to create high-quality still images.

Printers

• Printer output (on paper) is often called hard copy.

Features

• Resolution: measured in Dots Per Inch (DPI), typically 300, 600, or 1,200 in modern printers.  The more dots, the better the image, but the more ink that is used.  Photo printing uses even higher dpi printers (2,400 & 4,800 dpi)

NOTE: you can save ink if you adjust the settings to a lower DPI setting –
300 or 600 DPI often works well for plain text.

• Color capability: Black & White or color
• Speed: typically measured in Pages Per Minute (ppm).  Personal printers typically print 10-15 ppm for a single color (black) and 5-10 color
• Memory: most printers have on-board RAM to buffer the print so the computer is free to do other tasks.

Ink-Jet Printer

• Widely used technology that sprays small droplets of ink at high speed onto the surface of paper.
• They produce letter-quality images and prints in variety of colors.
• They are relatively inexpensive, quiet, and reliable.
• They are used in advertising and public relations where color and appearance is important.

Laser Printer

• Uses technology similar to a photocopying machine where a laser beam is used to produce images with excellent letter and graphics quality.
• They are more expensive than ink-jet printers but produce high-quality output.
• Two qualities are:
• Personal laser printers are cheaper and used by many single users.  They typically print 4 to 6 pages in a minute.
• Shared laser printers are more expensive and used by a group of users, and print at high speeds, print over 30 pages in a minute

Thermal Printer

• Uses heat elements to produce images on heat-sensitive paper.
• Previously used only in scientific labs to record data but recently being used to produce very high-quality color artwork and text.
• Not as common as Ink-Jet and Laser printers because of their cost and requirement of specially treated paper.

Other Printers

• Dot matrix printers: form characters and images using a series of small pins on a print head, they are inexpensive and reliable but quite noisy, used for tasks where high-quality is not required.
• Chain printers: used on a network connected to serve several computers or a mainframe computer requiring large quantities of printed output. They are expensive high-speed machines.
• Plotters: using output from digitizing tables and other graphics input devices they create maps, images, architectural and engineering drawings used by architects, engineers and graphic artists They can produce high-quality, multicolor documents and also documents that are larger that other printers cannot handle.

Audio Output Devices

• Translate audio information from the computer into sounds that people can understand.
• Most widely used devices are speakers and headphones
• These must be connected to a sound card in the system unit.
• Creating voice output is easier than recognizing voice input, and is used for many applications such as soda machines, telephones, and cars.

Combination Input and Output Devices

Fax machines

• Also know as Facsimile Transmission Machines, it’s an older technology used to transmit a “picture” of a document over telephone lines found in almost offices.
• To send fax, these devices scan the image of a document converting light and dark areas into a format that can be sent electronically over standard telephone lines.

Multifunction Devices (MFD) aka All In One (AIO) devices

• These devices combine the functions of a printer, scanner, copier, and fax into one unit.
• The advantage is it can save cost over buying separate units, as well as space.
• The disadvantage is the functionality may not be as good as separate machines, and if one goes bad, you may need to replace the whole device.

Internet Telephone

• Internet telephones typically connect to a system unit through a USB port and operate like a traditional telephone.
• Telephony, also known as Internet telephony, IP telephony and Voice Over IP (VoIP) – Note: IP = Internet Protocol uses the Internet rather than traditional communication lines to support voice communication.
• Convert analog voice into digital, and utilizes the Internet Protocol to send the digital signals.
• This technology is proving to be a popular, cost saving tool for both businesses and home users.
• Internet supported calls may have lower sound quality.

Terminals

• An input and output device that connect to a mainframe or host/server computer.
• The four kinds of terminals are:
• Dumb terminals: used to input and receive data, but cannot process data independently. Used to gain access to information from a computer. May be used by airline reservations agent for flight information stored on a mainframe computer.
• Intelligent terminals (Smart terminals) include a processing unit, memory and secondary storage. It is a microcomputer with communication software and a telephone link (modem) or other communication link.  Net PC (aka Net Personal Computer) is a low cost limited microcomputer with only a hard drive, sealed system unit and no expansion slots.
• Network terminal (aka thin client or network computer) is a low cost alternative to an intelligent terminal.  Most don’t have storage capabilities and must depend on a host computer or server for application and system software.
• Internet terminal (aka Web terminal or Web appliance) provides access to the Internet and display web pages on a standard television set. These special-purpose terminals offer Internet access without a microcomputer.