Question Bank for the Mid-Term Exams

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Chapter

Hardware: Input & Output

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Chapter Topics

UNIT 5A: Input Hardware

5.1 Keyboards

5.2 Pointing Devices

5.3 Source Data-Entry Devices

5.4 The Future of Input

UNIT 5B: Output Hardware

5.5 Softcopy Output: Display Screens

5.6 Hardcopy Output: Printers

5.7 Mixed Output: Sound, Voice, & Video

5.8 The Future of Output

5.9 Quality of Life: Health & Ergonomics

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Input Hardware

Devices that translate data into a form the computer can process

Translates words, numbers, sounds, and pictures into binary 0s and 1s (off or on electrical signals or light pulses)

Output Hardware

Devices that translate information processed by the computer into a form humans can understand

Translates binary code into words,

numbers, sounds, and pictures

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UNIT 5A: Input Hardware

The three major types of input hardware are keyboards, pointing devices, and source data-entry devices.

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5.1 Keyboards

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Keyboards: convert letters, numbers,

and characters into electrical signals

English keyboards differ from foreign language keyboards

How keyboards work:

You press a key

This interrupts the current flowing through the circuits

Processor determines where the break occurs

It compares the location of the break with the (x,y) character map for the language on the keyboard’s ROM chip

A character is stored in keyboard memory

(continued)

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Keyboards (continued)

The character is then sent to PC as a data stream via wire or wireless connection

OS interprets its own operating-system-specific commands and sends the others to the application for interpretation

Most keyboards are QWERTY – named for the first six letters on the top left of the keyboard.

Keyboards are either tactile (physical) or touch screen (virtual)

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Keyboard types

104 – 108 keys desktop standard

80 – 85 keys for laptops

Wired

Connect to CPU via a serial or USB port

Wireless use either

IR (infrared) technology

Radio Frequency (RF) technology

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Terminal Types

Dumb Terminals

a.k.a. Video Display Terminal (VDT)

Has display screen and keyboard

Can do input and output only – no data processing

Intelligent Terminals

Has screen, processor, keyboard, and memory

Can perform some independent functions

Automated teller machine; point-of-sale terminal; mobile data terminal

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5.2 Pointing Device

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Pointing devices include the mouse and its variants, the touch screen, and various forms of pen input.

Pointing devices control the position of the cursor or pointer on the screen and allow the user to select options displayed on the screen.

Mouse is the principal pointing device.

Mechanical mouse: a ball inside the mouse touches the desktop surface and rolls with the mouse.

Optical mouse: uses laser beams and special chips to encode data for the computer.

The mouse controls the mouse pointer on the screen – for example, an arrow, rectangle, pointing finger.

When the mouse pointer changes to an I-beam, that indicates that text can be entered.

The mouse has one to five buttons, used for various functions, such as clicking on and dragging items on the screen.

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Pointing Devices (continued)

Trackball

A movable ball mounted on top of a stationary device

Good for locations where a mouse can’t move around enough

Touchpad

To use: slide your finger over this small flat surface

Click by tapping you finger on the surface

May require more practice to use than a mouse

Used on laptops

Pointing stick

Located between the keys on a laptop keyboard, a pointing stick is a pressure-sensitive device that allows the user to control the pointer by directing the stick with one finger.

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Pointing Devices (continued)

Touch Screens

A video display screen sensitized to receive input from a finger touch.

Used in ATMs, information, kiosks, reservation kiosks, voting machines, cellphones, tablets, and e-books.

Multitouch Screens

Display screens that allow two or more fingers or other gestures such as pinching motions to be recognized as input at any one time. It allows pinching and stretching gestures on the screen to control zooming.

Pen input

Uses a pen-like stylus for input.

Uses handwriting recognition to translate cursive writing into data (handwriting recognition).

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Pointing Devices (continued)

Light pen

A light-sensitive penlike device that uses a wired connection to a computer terminal

Bring the pen to the desired point on the display screen and press a button to identify the screen location

Used by graphics artists, engineers, and in situations that require covered hands

Digitizer

Uses an electronic pen or puck to convert drawings

and photos to digital data

Digitizing tablets are often used in architecture

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Pointing Devices (continued)

Digital Pen

Writing instrument

Writers can write on paper

A tiny camera in the pen tip captures the writing

A microchip in the pen converts the pen to digital ink

The writing is sent as an image file to the computer

Some versions require special paper

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5.3 Source Data-Entry Devices

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Scanning & Reading Devices—Source data-entry devices that create machine-readable data and feed it directly into the computer (no keyboard is used)

Scanners

Use light-sensing equipment to translate images of text, drawings, and photos into digital form

Image scanners are used in electronic imaging

Resolution refers to the image sharpness, measured in dots per inch (dpi)

Flatbed scanners work like photocopiers – the image is placed on the glass surface, then scanned

Other types are sheet-fed, handheld, and drum

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Bar-Code Readers (source data entry)

Photoelectric (optical) scanners that translate bar code symbols into digital code

The digital code is then sent to a computer

The computer looks up the item and displays its name and associated information

Bar code types

1D (regular vertical stripes) holds up to 16 ASCII characters

2D (different-sized rectangles) can hold 1,000 to 2,000 ASCII characters

3D is “bumpy” code that differentiates by symbol height

Can be used on metal, hard rubber, other tough surfaces

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Radio-Frequency Identification (RFID)

Based on an identifying tag bearing a microchip that contains specific code numbers. These code numbers are read by the radio waves of a scanner linked to a database.

Active RFID tags have their own power source and can transmit signals over a distance to a reader device.

Passive RFID tags have no battery power of their own and must be read by some sort of scanner.

RFID tags of both types are used for a wide range of purposes and are starting to replace bar codes in many situations.

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Mark Recognition Readers (source data entry)

MICR – magnetic-ink character recognition

Uses special magnetized inks

Must be read by a special scanner that reads this ink

Used on bank checks

OMR – optical mark recognition

Uses a special scanner that reads

bubble (pencil) marks

Used in standardized tests such as the

SAT and GRE

OCR – optical character recognition

Converts scanned text from images (pictures of the text) to an editable text format

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Image-Capture Devices

Digital Cameras

Use a light-sensitive processor chip to capture photographic images in digital form and store them on a small disk in the camera or on flash memory cards.

Most can be connected to a PC by USB; smartphones include digital cameras.

Webcams

Video cameras attached to a computer to record live moving images then post them to a website in real time.

Can be attached externally or built into the computer/device.

Frame-grabber video card

Can capture and digitize 1 frame at a time

Full-motion video card

Can convert analog to digital signals at rates up to 30 frames per second

Looks like a motion picture

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Digital Camera

Audio-Input Devices

Record analog sound and translate it into digital files for storage and processing

Two ways to digitize audio (often via microphone)

Sound Board

An add-on board in a computer that converts analog sound to digital sound, stores it, and plays it back to speakers or amp

MIDI Board

Stands for Musical Instrument Digital Exchange

Uses a standard for the interchange between musical instruments, synthesizers, and computers

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Speech-Recognition Systems

Use a microphone or telephone as an input device. Converts a person’s speech into digital signals by comparing against 200,000 or so stored patterns.

Used in places where people need their hands free – warehouses, car radios, stock exchange trades.

Helpful for people with visual or physical disabilities that prevent them from using other input devices.

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Speech Recognition

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Sensors

Input device that collects specific data directly from the environment and transmits it to a computer.

Can be used to detect speed, movement, weight, pressure, temperature, humidity, wind, current, fog, gas, smoke, light, shapes, images, earthquakes, etc.

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Biometric-Input Devices

Biometrics is the science of measuring individual body characteristics, then using them to identify a person through a fingerprint, hand, eye, voice, or facial characteristics.

Example: notebook computers equipped with biometric sensors that read fingerprints, instead of passwords, before allowing access to networks.

Airport and building security systems use biometrics.

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5.4 The Future of Input

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Data will be input from more and more locations.

Use of source data entry will increase.

Better input devices for people with disabilities

Better speech recognition

Better touch and gesture-recognition input

Pattern recognition and improved biometrics

Brainwave input devices

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UNIT 5B: Output Hardware

Softcopy = data shown on a display screen or is in audio or voice form; it exists only electronically. This kind of output is not tangible; it cannot be touched. You can touch disks on which programs are stored, but the software itself is intangible.

Hardcopy = tangible output, usually printed. The principal examples are printouts, whether text or graphics, from printers. Film, including microfilm and microfiche, is also considered hardcopy output.

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5.5 Softcopy Output

Display Screens

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Features of display screens to consider include screen dimension, screen clarity, and color and resolution standards.

Screen size & aspect ratio

The active display area is the size of a computer screen measured diagonally from corner to corner in inches.

Desktop computers are commonly 15–30 inches (laptops 12–18 inches, tablets 8.4–14.1 inches, and smartphones 2.5–4.1 inches).

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The aspect ratio is the proportional relationship of a display screen’s width and height.

Standard displays have a 4:3 aspect ratio (4 units wide to 3 units high); wide-screen displays have 16:9 or 16:10.

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Screen Clarity

Dot pitch (dp) is the amount of space between adjacent pixels (square picture elements) on screen.

The closer the pixels, the crisper the image.

Get .25 dp or better.

Resolution refers to the image sharpness.

The more pixels, the better the resolution.

Expressed in dots per inch (dpi) .

pixel

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Screen Clarity (continued)

Color depth (bit depth) is the number of bits stored in a dot (pixel).

The higher the number the more true the colors.

24-bit color depth is better than 8-bit color depth, but it needs more video card memory.

Refresh rate is the number of times per second the pixels are recharged – a higher rate gives less flicker.

Standard bit depths

for color

8-bit—256 colors

16-bit—65,536 colors

24-bit—16,777,216 colors

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Microcomputers come with graphics cards (video cards) that work with the screen.

Graphics cards have their own memory (VRAM), which stores each pixel’s information.

The more VRAM, the higher the resolution you can use.

Desktop publishers, graphics artists, and gamers need lots of VRAM.

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Types of Display Devices

The most common type of display screens, flat-panel displays are made up of two plates of glass separated by a layer of a substance in which light is manipulated.

One type of flat-panel display is the liquid crystal display (LCD), in which molecules of liquid crystal line up in a way that alters their optical properties, creating images on the screen by transmitting or blocking light.

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Other types of displays:

Plasma displays: A layer of gas is sandwiched between two glass plates, and when voltage is applied, the gas releases ultraviolet light, which activates the pixels on the screen and forms an image. Although expensive, plasma monitors offer brighter colors and screen sizes up to 150 inches wide; however, they usually do not last as long as other display types.

Cathode-ray tube (CRT) and others: Falling out of use.

Multiple screens: Splitting the monitor display area into multiple screens, to view different documents at once.

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5.6 Hardcopy Output

Printers

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Printers print text and graphics on paper or other hardcopy materials.

Printer resolution is measured by dpi (dots per inch); 1,200 x 1,200 is the most common for microcomputers.

Printers are either impact or nonimpact – impact printers (dot-matrix printer) print by striking the paper directly; nonimpact printers (such as laser printers and inkjet printers) do not have direct contact with the hardcopy medium.

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Like a dot-matrix printer, a laser printer creates images with dots. However, as in a photocopying machine, these images are produced on a drum, treated with an electrically charged inklike toner (powder), and then transferred from drum to paper.

Laser printers run with software called a page description language (PDL) , which tells the printer how to lay out the printed page and supports various fonts.

A laser printer comes with one or both types of PDL: PostScript or PCL (Printer Control Language. In desktop publishing, PostScript is the preferred PDL.

Laser printers have their own CPU, ROM, and memory (RAM), usually 16 megabytes (expandable generally up to 512 megabytes for higher-cost printers).

When you need to print out graphics-heavy color documents, your printer will need more memory.

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Laser Printer

Inkjet printers spray onto paper small, electrically charged droplets of ink from four or more nozzles through holes in a matrix at high speed.

Like laser and dot-matrix printers, inkjet printers form images with little dots. Inkjet printers commonly have a dpi of 4,800 x 1,200; they spray ink onto the page a line at a time, in both high-quality black-and-white text and high-quality color graphics.

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Inkjet Printer

Nonimpact printers also include:

Thermal printers: Low- to medium-resolution printers that use a type of coated paper that darkens when heat is applied to it; typically used in business for bar-code label applications and for printing cash register receipts.

Thermal wax-transfer printers: Print a wax-based ink onto paper. After it becomes cool, the wax adheres permanently to the paper. Because of their waterfastness, these labels find uses in industrial label printing.

Photo printers: Specialized machines for printing continuous-tone photo prints , with special paper and color dyes.

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Multifunction printers

Printers that combine several capabilities:

Printing

Scanning

Copying

Faxing

Cost less and take up less space than buying the four separate office machines.

But if one component malfunctions, so will the other functions.

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Plotters : Designed for large-format printing

Specialized output device designed to produce large high-quality, 3-D graphics in a variety of colors.

Used by architects, engineers, and map-makers.

Pen plotters use one or more colored pens.

Electrostatic plotters lie partially flat on a table and use toner as photocopiers do.

Large-format plotters are large-scale inkjet printers used by graphic artists.

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5.7 MIXED OUTPUT: SOUND, VOICE, & VIDEO

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Mixed Output: Sound, Voice, & Video

Sound output—produces digitized sounds, even “3-D” sound.

You need a sound card and sound software.

Good speakers can improve the sound.

Voice output—converts digital data into speechlike sounds.

Used in phone trees, cars, toys and games, GPS systems, and TTS (text-to-speech) systems for hearing-impaired people.

Video output—photographic images played quickly enough to appear as full-motion.

Requires powerful processor and video card.

Video files are large, so a lot of storage is needed, too.

Videoconferencing is a form of video output.

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5.8 The Future of Output

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More unusual forms of output

More data used in (Big Data)

More realistic output

Better and cheaper display screens

Printers that use less ink

Movie-quality video for PCs

Increased use of 3D output

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5.9 Quality of Life

Health & Ergonomics

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Health Matters

Overuse injuries and repetitive stress injuries:

Result when muscle groups are forced through fast, repetitive motions.

May effect data-entry operators who average 15,000 keystrokes an hour.

May effect computer users whose monitor, keyboard, and workstation are not arranged for comfort.

Carpal tunnel syndrome: Caused by pressure on the median nerve in the wrist, through short repetitive movements.

Eyestrain, headaches, back and neck pains can be problems.

Electromagnetic fields may be harmful.

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Ergonomics is the methodology of designing a workplace to make working conditions and equipment safer and more efficient.

Keyboards must be placed at the correct height depending on each worker’s size; detachable keyboards are useful.

Monitor refresh rates must be fast enough to avoid eyestrain.

Monitor heights must be correct for comfortable viewing; use a tilting screen.

Wrist rests may help avoid carpal tunnel syndrome.

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