The Computer

Prelim

Text Entry Devices

These are keyboards, phone pads, handwriting and speech recognition.

Keyboards

• The most common text input device

• Allows rapid entry of text by experienced users

QWERTY Keyboard

• standard keyboard layout but non-alpha numeric keys are placed differently

• They are not optimal for typing

• Alt designs allow faster typing but people are reluctant to change

Alphabetic Keyboard

• The keys are arranged in an alphabetical order

• Does not improve typing performance

DVORAK Keyboard

• Layout where common letters are under dominant fingers - For right handed use

• Improvement on speed performance and fatigue

Special Keyboards

• Designed to reduce fatige for repetitive strain injury

• Ex. Maltron left-handed keyboard

Chord Keyboard

• Only 4 or 5 key combination of keypresses

• Compact in size

Phone Pad & T9 Entry

• Older phones use them

• Use numeric keys with multiple presses.

Handwriting Recognition

• Text can be inputted using pen and tablet

Speech Recognition

• Limited vocabulary systems

• Problems with external noise

• But rapidly improving

Numeric Keypads

• For entering numbers quickly

• Ex. Calculators, telephones, etc.

Positioning/Pointing/Drawing Devices

Devices like mouse, touchpads, joysticks, etc.

Mouse

• Handheld pointing device that is common and easy to use

• Planar movement and has some buttons

Mechanical Mouse

• Has a ball underside of the mouse

• Rotates orthogonal potentiometers

Optical Mouse

• Has Light emitting diode on underside of the mouse

• Detects flunctuating alterations in reflected light intensity

Footmouse

• Controls mouse movement with feet, not common

• Ex. Car pedals, sewing macine, organ/piano pedals, etc.

Touchpads

• Are touch sensitive tablets on a laptop, operated by sliding a finger

Trackball

• The ball is rotated inside a static housing

Thumbwheels

• Manipulate horizontal and vertical movement of the cursor

Joystick

• Uses indirect pressure of stick for velocity lf movement

• Has buttons for selection

• Ex. Used in videogames, aircraft controls, 3D Navigation systems, etc.

Keyboard Nipple

• It is a miniature joystick on a keyboard

Touch-Sensitive Screen

• It detects the presence of a finger or stylus on the screen

Stylus Pen

• It is a small pen-like pointer to draw on a screen.

• Uses touch sensitive surface or magnetic detection

Digitizing Tablet

• Is a mouse-like device with crosshairs

• Use on special surface

Eyegaze Technology

• Controls computer by tracking the eyes.

Cursor Keys

• Are 4 Keys (Up, down, left, right) in standard inverted T layout

Discrete Positioning Controls

• Mainly used in menu selection in phones, TV controls, etc.

Display Devices

Devices like CRT & LCD Screens

Screen

It is a vast number if colored dots

Bitmap-Base

It means that the display is made of a fixed number of dots or pixels in a rectangular grid

Anti-Aliasing

It is the softening of edges of the segments

Cathode Ray Tube (CRT)

• Uses stream of electrons emitted from electron gun, focused and directed by magnetic fields, hit phosphor-coated screen which glows

Liquid Crystal Displays (LCD)

• Smaller, lighter, and no radiation problems

• Found in most modern screens

Large Displays

Used for meetings, lectures, etc.

Situated Displays

Displays information relevant to public location

Digital Paper

• Also known as interactive paper

• Used with a digital pen to create handwritten digital documents

Virtual Reality/ 3D Interaction

Devices that utilize positioning in 3D space, moving and grasping.

VR Helmet

• Detect head motion and possibly eye gaze

• Small TV screen for each eye

Whole Body Tracking

• Accelerometers strapped to limbs and reflective dots for video processing.

Data Glove

• Fiber optics sued to detect finger position

VR Caves/Simulators

• Scenes projected on walls

• Realistic environment

• Hydraulic rams and real controls

Physical Controls and Sensors

Devices that have special displays and gauges, etc.

Analogue Presentations

• Sensor presentations that uses dials, gauges, lights

Digital Displays

• Sensors that utilize LCD screens, LED lights, etc.

Heads-Up Displays

• These are most often found in aircraft cockpits

• Shows most important controls depending on context

Sounds

• Audio cues such as beeps, clonks, whistles, and whirrs

• Used for errors

• Confirmation of actions

Touch

• Cues such as vibrations.

• Feedback in games

• Are haptic devices

Physical Controls

• These are specialist controls for industrial and consumer products

Printing & Scanning

Are Print technologies, most common printers today are dot-based

Fonts

• The particular type of text

• Size measured in points (1 pt about 1/72) related to its height

Sans-Serif Fonts

• Uses square ended strokes

Serif Fonts

• Fonts with splayed ends

lowercase

• Used to easily read shape of words

UPPERCASE

• Used for individual letters and non-words

Serif Fonts

• Helps your eye on long lines of printed text

Scanners

• Takes paper and convert it into a bitmap

• Resolutions range from 600-2400 dpi

Optical Character Recognition (OCR)

• It converts bitmap back into text

Memory

Capacities, compression formats, access, etc.

Short-Term Memory (RAM)

• Random Access Memory

• RAM is volatile, content is lost when power is turned-off

Long-Term Memory (Disks Drives, etc.)

• Are Magnetic Disks (Hard disks, tapes) and Optical Disks (CD-ROM, DVD)

• It is rather slow

Compression

• It reduces amount of storage required