Module 4; Input & Output

Input

• any data and instructions entered into the memory of a computer. 

• An input device converts data that humans can understand (text, images, voice, etc.) into a form (0s and 1s) that the computer can process.

virtual keyboard:

• these keyboards are used primarily with mobile devices and tablets.

laptop keyboard

• these keyboards are smaller than traditional keyboards and are widely used on laptop computers.

thumb keyboard:

• these keyboards are used on smartphones and other small mobile devices. Designed primarily for communicating via texting and connecting to the web, these keyboards are very small.

traditional keyboard:

• These full-size keyboards are widely used on desktops and larger computers.

Mouse

• controls a pointer that is displayed on the monitor

Touchpad

• used to control the mouse pointer and to make selections. They operate by moving or tapping your finger on the surface of a pad. These devices are widely used instead of a mouse with laptops and some types of mobile devices

Trackball

• a stationary computer pointing device featuring a movable ball resting in a socket

Touch screens

• allows users to select actions or commands by touching the screen with a finger or penlike device

Electronic pen (also called a stylus)

• is used with many types of input devices, such as digital writing systems, graphics tablets and signature capture devices)

Motion input:

• control games by user movements. For example, Microsoft's Kinect accepts user movements and spoken commands to control games on the Xbox 360.

Audio (voice input, music input)

• convert sounds into a form that can be processed by the system unit. By far the most widely used device is the microphone.

Webcam

• specialized digital video cameras that capture images and send them to a computer for broadcast over the Internet.

Optical scanners (flatbed or portable)

• accepts documents consisting of text and/or images and converts them to machine-readable form

These devices do not recognize individual letters or images. Rather, they recognize light, dark, and colored areas that make up individual letters or images.

• four types: flatbed, document, portable, and 3D.

Optical character recognition (OCR)

• uses special preprinted characters that can be read by a light source and changed into machine-readable code. The most common is the handheld wand reader. These are used in department stores to read retail price tags by reflecting light on the printed characters.

Optical mark readers (OMR):

• senses the presence or absence of a mark, such as a pencil mark. often used to score standardized multiple-choice tests.

Barcode readers:

• These devices are either handheld wand readers or platform scanners. They contain photoelectric cells that scan or read bar codes, or the vertical zebra-striped marks printed on product containers.

RFID readers (radio-frequency Identification)

•  tiny chips that can be embedded in most everything. They can be found in consumer products, driver's licenses, passports, and any number of other items.

• These chips contain electronically stored information that can be read using an RFID reader located several yards away.

  • They are widely used to track and locate lost pets; to monitor production and update inventory; and to record prices, product descriptions, and locations of retail items.

Magnetic stripe readers

• a hardware device that extracts encoded data from the strip on the back of a card

Biometric readers (fingerprint, face, iris)

• uses digital imaging technology and sophisticated algorithms to analyze fingerprints and other biometric data.

Output

• data that has been processed into a useful form.

• An output device converts machine language (0s and 1s) into a form that people can understand (text, images, audio, video).

  • The most common output devices are monitors, printers, and speakers.

Most monitors use

• either liquid crystal display (LCD) or light emitting diode (LED technology to display an image.

Monitor characteristics include:

•  Size (measured diagonally): desktops vary from 19” to 30”, laptops vary from 11” to 17”.

• Screen resolution: the quality of the screen image. 

  • Resolution is measured by columns and rows of pixels. A pixel is a very small area (dot) on the computer screen that displays a color. When thousands of colored dots are arranged together, it creates an image on the monitor. Common resolution sizes range from 800 x 600 to 1920 x 1080. The higher the resolution, the more pixels, and the better the picture quality.

Output only vs touch screen input with output

• A graphic processing unit (GPU) is a device that works with the CPU to process graphic data and send the data to the monitor. A GPU is built into a graphics card (also known as a video card). Video cards can be purchased and installed inside a desktop computer to upgrade the computer’s video capabilities. An integrated graphics component is built directly into the motherboard or CPU.

Upgrading a computer’s video card can not only improve the quality of the screen image, but also system performance. The video card (or integrated graphics component) determines many

• display characteristics:

• Available screen resolutions

• The number of bits used to store color information for each pixel

• The total number of colors used to display images

• The number of monitors that can be connected to the computer

•  The type of connectors that can be used to connect a monitor to a computer

•  Most video cards contain their own memory (called video RAM or VRAM) to help in processing graphic output

Data printed on paper is referred to as a hard copy. Data displayed on a monitor is called soft  copy.

• Printers produce text and graphics on paper. Most printers used today are nonimpact printers, which means that no part of the printer actually touches the paper.

All nonimpact printers

• form images by grouping together hundreds of dots. The two most common types of nonimpact printers are ink-jet and laser.

Printer characteristics include:

• Print resolution

• Print resolution

• Printer speed

• Local or Network

• Traditional vs multifunction

Print resolution

• measured in dots per inch (dpi). The greater the print resolution, the better the quality of the printout.

Print resolution

• ranges from 300-700 dpi for ink-jet printers and from 600-2,400 dpi for laser printers.

Printer speed

• typically measured in pages per minute (ppm). Ink-jet printers typically print between 5-40 ppm; laser printers typically print from 20-100 ppm.

Local or Network

• Local (personal) printers are designed to be connected to onecomputer.

• Network printers are designed to be connected to a network and shared by multiple users.

Traditional vs multifunction:

• Traditional printers only provide print functionality; multifunction printers can provide print copy, scan, and fax capabilities

Ink-jet printers

• spray tiny drops of liquid ink from one or more ink cartridges onto the paper.

• They generally cost between $75 and $300. Due to their lower cost, ink-jet printers are the most popular printer for personal use.

Laser printers

• use toner powder released from a toner cartridge.

• The toner powder is applied to a drum. When paper is rolled over the drum the toner powder is applied to the paper.

• Laser printers generally cost between $100 and $1,000.

• Due to the higher speeds and better print quality laser printers are normally purchased for business use.

3-D printers

• create objects by adding material such as plastic, metal, ceramic, wood or glass to a three-dimensional object, one horizontal layer at a time. 3-D printers can print solid objects such as clothing, toys, jewelry and manufacturing parts.

Photo printers

• are used to print high quality photos

Label printers

• print labels with adhesive material that can be placed on clothing, envelopes, packages and file folders.

Plotters

• produce high-quality drawings, blueprints and maps using a variety of paper sizes

 Large format ink-jet printers

• print posters, signs and banners onto very wide paper, fabric and other types of materials.

Impact printers

• print heads that strike ink against the paper. They are used in applications that require multipart forms (normally white, yellow and pink).

Speakers provide audio output for games, music, movies, telephony, and videoconferencing applications. 

• traditional speakers people can use headphones, earbuds or headsets. Headsets provide both audio output and voice input functionality.

The Americans with Disabilities Act (ADA)

• any company with 15 or more employees to make reasonable attempts to accommodate the needs of physically challenged workers.

• Hardware and/or software that enables disabled individuals to use a computer is called assistive technology.

Examples of assistive technology include:

• Input devices:

• Output devices:

Input devices:

• Voice recognition audio input

•  On-screen touch keyboards

• Braille keyboards

• Head mounted pointers to control the pointer or insertion point

Output devices:

• Programs that display words instead of sounds

• Programs that read the text information on the monitor (screen readers)

• Braille printers