HCI 2ND QUIZ REVIEWER

input devices

 text entry and pointing

output devices

screen (small & large), digital paper

virtual reality

special interaction and display devices

physical interaction

e.g. sound, haptic, bio-sensing

paper

as output (print) and input (scan)

memory

RAM & permanent media, capacity & access

processing

speed of processing, networks

Keyboards

Most common text input device, Allows rapid entry of text by experienced users

QWERTY

Standardized layout but non-alphanumeric keys are placed differently and accented symbols needed for different scripts

Alphabetic

keys arranged in alphabetic order

Dvorak

common letters under dominant fingers, biased towards right hand

Chord keyboards

only a few keys - four or 5 letters typed as a combination of keypresses and has compact size

phone pad and T9 entry

use numeric keys with multiple presses

Handwriting recognition

Text can be input into the computer, using a pen and a digesting tablet

Mouse

Handheld pointing device

planar movement and buttons

Two characteristics of mouse

Mechanical

Ball on underside of mouse turns as mouse is moved, Rotates orthogonal potentiometers

Optical

light emitting diode on underside of mouse, may use special grid-like pad or just on desk

Footmouse

controlling mouse movement with feet

Touchpad

small touch sensitive tablets, stroke’ to move mouse pointer

Trackball

is a pointing device consisting of a ball held by a socket containing sensors to detect a rotation of the ball about two axes

Joystick

buttons for selection on top or on front like a trigger, often used for computer games aircraft controls and 3D navigation

Keyboard nipple

for laptop computers, miniature joystick in the middle of the keyboard

Touch-sensitive screen

Detect the presence of finger or stylus on the screen.

Stylus

small pen-like pointer to draw directly on screen, may use touch sensitive surface or magnetic detection

Light Pen

now rarely used, uses light from screen to detect location

Digitizing tablet

Mouse like-device with cross hairs, used on special surface - rather like stylus

Eyegaze

control interface by eye gaze direction, uses laser beam reflected off retina, mainly used for evaluation (ch x) and potential for hands-free control

Cursor keys

Four keys (up, down, left, right) on keyboard. No standardized layout, but inverted “T”, most common

bitmap

Virtually all computer displays are based on some sort of ________

screen

is vast number of colored dots or pixels in a rectangular grid

Resolution

number of pixels on screen (width x height) or density of pixels (in pixels or dots per inch - dpi)

colormap

The set of colors make up what is called the __________

Aspect ratio

ratio between width and height

256

______ from a palette

Jaggies

diagonal lines that have discontinuities in due to horizontal raster scan process

Anti-aliasing

softens edges by using shades of line colour, also used for text

Cathode ray tube

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

Liquid crystal displays

Smaller, lighter, and … no radiation problems.

plasma

usually used for wide screen

situated displays

displays in ‘public’ places, large or small

Digital paper

thin flexible sheets, updated electronically, but retain display

cockpit and virtual controls

steering wheels, knobs and dials … just like real!

3D mouse

six-degrees of movement: x, y, z + roll, pitch, yaw

Yaw

left/right orientation

Roll

the amount it is twisted about its own axis

Pitch

up/down angle

data glove

fibre optics used to detect finger position

VR helmets

detect head motion and possibly eye gaze

whole body tracking

accelerometers strapped to limbs or reflective dots and video processing

desktop VR

ordinary screen, mouse or keyboard control, perspective and motion give 3D effect

conflicting cues

______ => sickness

analogue representations

dials, gauges, lights, etc.

digital displays

small LCD screens, LED lights, etc.

head-up displays

found in aircraft cockpits, show most important control

Sounds

used for error indications

Environment and bio-sensing

sensors all around us

Printing

image made from small dots

resolution

size and spacing of the dots, measured in dots per inch (dpi)

speed

usually measured in pages per minute

Dot-Matrix Printers

use inked ribbon (like a typewriter), line of pins that can strike the ribbon, dotting the paper

80-120 dpi

typical resolution of dot matrix printers

Ink-Jet And Bubble-Jet Printers

tiny blobs of ink sent from print head to paper

300 dpi or better

typical resolution of Ink-Jet And Bubble-Jet Printers

Laser Printer

like photocopier: dots of electrostatic charge deposited on drum, which picks up toner (black powder form of ink) rolled onto paper which is then fixed with heat

600 dpi or better

typical resolution of Laser Printer

Shop Tills

dot matrix, same print head used for several paper rolls, may also print cheques

Thermal Printers

special heat-sensitive paper, paper heated by pins makes a dot                              

Font

the particular style of text

fixed-pitch

every character has the same width, e.g. Courier

variable-pitched

some characters wider e.g. Times Roman

sans-serif

square-ended strokes e.g. Helvetica

serif

with splayed ends (such as) e.g. Times Roman or Palatino

lowercase

easy to read shape of word

UPPERCASE

better for individual letters and non-words

serif fonts

helps your eye on long lines of printed text, but sans serif often better on screen

PostScript

is the most common programming language(PL for printing)

SCANNERS

Take paper and convert it into a bitmap

flat-bed

paper placed on a glass plate; whole page converted into bitmap

hand-held

scanner passed over paper, digitizing strip typically 3-4” wide

600– 2400 dpi

Typical resolutions of scanners

OCR

_______ converts bitmap back into text

paper

usually regarded as output only

glyphs

small patterns of /\\//\\\

silicon chips

Random access memory (RAM) on __________

10 nano-second

RAM access time

100 Mbytes/sec

data transferred at around __________

Magnetic Disks

store around 1.4 Mbytes, hard disks typically 40 Gbytes to 100s of Gbytes access time ~10ms, transfer rate 100kbytes/s

Optical Disks

use lasers to read and sometimes write, more robust that magnetic media

PDAs

often use RAM for their main memory

Flash-Memory

used in PDAs, cameras etc., silicon based but persistent

2Mb

this book, text only 320,000 words, how many mb?

4.5 Mbytes

the Bible, how many mb

128 Mbytes

scanned page, how many mb

10 Mbytes

digital photo, how many mb

10 Mbytes

video, how many mb per second

JPEG                                           

lose rapid changes and some colour   

MP3

reduce accuracy of drowned out notes

ASCII

7-bit binary code for to each letter and character (The basic standard for text storage)

UTF-8

8-bit encoding of 16 bit character set (UNICODE standard)