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Questions and Answers
The movement of the mouse moves the screen ______.
cursor
Mouse movement is generally detected in the (x, ______) plane.
z
The ______ method involves a ball on the underside of the mouse that turns as it is moved.
mechanical
Optical mice use a ______ emitting diode on the underside to detect motion.
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A ______ is a small touch-sensitive tablet used mainly in laptop computers.
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Trackball devices allow for cursor movement by rotating a ball inside a ______ housing.
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A joystick translates the pressure of the stick into ______ of movement.
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A touch-sensitive screen detects the presence of a finger or ______ on the surface.
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Anti-aliasing softens edges by using shades of line ______.
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A cathode ray tube is used in ______ and computer monitors.
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The stream of electrons in a cathode ray tube hits a phosphor-coated ______, which glows.
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Health hazards of CRT include exposure to ______, which is largely absorbed by the screen.
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One health hint suggests not to sit too close to the ______.
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Liquid crystal displays are notably smaller, lighter, and have no ______ problems.
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In LCDs, light passes through the top plate and crystal, then reflects back to the ______.
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Large displays are commonly used for ______, lectures, and other group presentations.
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A ______ is usually wide screen and utilizes plasma technology.
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Situations involving ______ displays relate the meaning of information to the location.
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Digital paper consists of thin, flexible sheets that are updated electronically and can retain their ______.
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Projected displays may be obscured by the ______ or body of the presenter.
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Interactive displays often require a ______ or touch-sensitive screen for user interaction.
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The ______ changes when the matrix of light beams is interrupted.
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A ______ is a small pen-like pointer used to draw directly on the screen.
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The ______ uses light from the screen to detect its location.
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Eyegaze control interfaces mainly use a ______ beam reflected off the retina.
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Cursor keys are very cheap but ______.
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Bitmap displays consist of a vast number of ______ dots.
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Resolution is often defined in terms of the number of ______ on the screen.
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Anti-aliasing helps to smooth out ______ in digital images.
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A computer system is made up of various ______.
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Input devices include text entry and ______.
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Output devices can be a screen or ______.
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Virtual reality involves special interaction and ______ devices.
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A typical computer system includes a screen, keyboard, and ______.
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Most computing today is ______, allowing for rapid feedback.
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Older computing methods involved ______ processing with long wait times.
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Users often prefer to be ______ rather than just think during interactions.
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Study Notes
Computer Systems Components
- A computer system has various components that affect user interaction
-
Input Devices:
- Text entry (keyboard)
- Pointing (mouse, trackpad)
- Virtual reality devices
- Physical interaction devices (sound, haptic, bio-sensing)
- Paper (scan)
-
Output Devices
- Screens (small & large)
- Digital paper
- Paper (print)
-
Memory
- RAM (Random Access Memory)
- Permanent Media
- Capacity (how much data can be stored)
- Access (how quickly data can be retrieved)
-
Processing
- Speed of processing
- Networks
Interacting with Computers
- Understanding computers and their components is crucial for understanding human-computer interaction, focusing on:
- What goes in and out (devices, paper, sensors)
- What the computer can do (memory, processing, networks)
Typical Computer Systems
- Common elements include:
- Screen or Monitor (with windows)
- Keyboard
- Mouse or Trackpad
- Variations:
- Desktop
- Laptop
- PDA (Personal Digital Assistant)
- The chosen devices dictate the style of interaction supported by the system.
Interactivity Through Time
-
Batch Processing (past):
- Punched cards or data files prepared
- Long wait for processing and output
- Limited user interaction
-
Interactive Computing (present):
- Rapid feedback
- User in control (often)
- Emphasis on doing rather than thinking
Mouse and Other Pointing Devices
-
Mouse:
- Movement of the mouse moves the screen cursor.
- Indirect Manipulation: device does not obstruct the screen.
- Advantages: accurate, fast, versatile
- Disadvantages: hand-eye coordination challenges for beginners
-
Mouse Motion Detection:
- Mechanical: Ball on the underside rotates potentiometers.
- Optical: Emits light to detect movement on surfaces.
-
Other Devices:
- Footmouse: experimental and uncommon
- Touchpads: used in laptops, good acceleration settings important
- Trackball: ball rotated inside a housing, indirect, fast for gaming
- Thumbwheels: accurate for CAD and fast scrolling
- Joystick: indirect, pressure = velocity, often for gaming
- Keyboard Nipple: miniature joystick on laptops
- Touchscreen: direct pointing, finger or stylus, good for menu selection, susceptible to finger marks and imprecision.
- Stylus: pen-like pointer, used in PDA, tablets, and drawing tables
- Light Pen: rare, uses light from screen to detect location
- Eyegaze: uses reflected laser beam for selection, potential for hands-free control, accuracy varies, used for research
- Cursor Keys: Four arrow keys, cheap, slow, good for basic text editing tasks.
- Discrete Positioning Controls: Cursor pads or mini-joysticks in phones, TV controls, etc. for menu selection
Display Devices
-
Bitmap Screens:
- Cathode Ray Tube (CRT)
- Liquid Crystal Display (LCD)
- LED (Light-Emitting Diode)
- Plasma
-
Large & Situated Displays:
- Used for presentations, lectures, public spaces, and information display
- Types: Plasma, video walls, projectors (front and back)
-
Digital Paper:
- Thin flexible sheets that display and retain content
- Uses small spheres or colored liquids to create images
- Rapidly developing technology
Bitmap Displays
- Resolution: Number of pixels (dots) on the screen (width x height)
- Pixel Density: Measured in dots per inch (dpi)
- Aspect Ratio: Ratio between width and height (e.g., 4:3, 16:9)
- Colour Depth: Number of colours per pixel (black/white, palettes, 24-bit for millions of colors)
- Anti-aliasing: Softens edges to reduce jaggedness, uses shades of color for smoother lines and text.
Cathode Ray Tube (CRT)
- How it Works: Electron gun emits electrons that hit a phosphor-coated screen to create light.
-
Health Hazards:
- X-rays, UV and IR radiation (minimal)
- Radio frequency emissions and ultrasound.
- Electrostatic fields (rashes possible)
- Electromagnetic fields (potential impact on visual system and reproductive health)
-
Health Tips:
- Maintain distance, use larger fonts, take breaks, avoid bright lights, use good lighting, extra precautions during pregnancy.
Liquid Crystal Display (LCD)
- Smaller, lighter, no radiation hazards
- Used in PDAs, laptops, desktops, TVs, and dedicated displays
-
How it Works:
- Liquid crystals between polarized plates change their alignment depending on voltage to control light transmission.
- Less eye strain than CRTs because light is reflected, not emitted.
Large Displays
- Purpose: Meetings, lectures, public information displays
- Types: Plasma, Video Walls, Projectors (front & back projected)
Situated Displays
- Displays located in public spaces
-
Types:
- Information displays (non-interactive)
- Interactive displays (with touchscreens or styluses)
- Location Matters: Meaning and interaction are context-dependent.
Hermes Situated Display Example
- Small displays beside office doors for handwritten notes.
- Office owner views the notes via a web interface.
Digital Paper
- Thin and flexible
- Electronic updates but retains the display
- Uses turning spheres or channels with colored liquids and contrasting spheres to form images.
Digital Information Interaction Summary:
- Computer systems are composed of various components that influence human-computer interaction.
- Input and output devices, memory, and processing capabilities all play significant roles.
- Interactive computing has evolved from batch processing, enabling rapid feedback and user control.
- Display devices, such as CRTs, LCDs, and digital paper, present information visually.
- The placement and design of devices impact how users interact with information.
- Understanding the characteristics of various devices and their associated technologies is crucial for creating effective and user-friendly interactions.
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Description
Test your knowledge on the various components of computer systems and how they interact with users. This quiz covers input and output devices, memory types, processing capabilities, and the overall architecture of typical computer systems. Understand how these elements contribute to human-computer interaction.
