Plan : Introduction Introduction 1. Text entry devices 2.
Positioning, pointing and drawing 3. Devices for virtual reality
and 3D interaction 4. Physical controls, sensors and special
devices 5. Paper: printing and scanning 6. Memory 2
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a computer system is made up of various elements each of these
elements affects the interaction 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 3 1.
INTRODUCTION
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to understand humancomputer interaction need to understand
computers! what goes in and out devices, paper, sensors, etc. what
can it do? memory, processing, networks
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1. INTRODUCTION A typical computer system: screen, or monitor,
on which there are windows keyboard mouse/trackpad variations
desktop laptop PDA the devices dictate the styles of interaction
that the system supports If we use different devices, then the
interface will support a different style of interaction
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Computers are coming out of the box! Information appliances are
putting internet access or dedicated systems onto the fridge,
microwave and washing machine: to automate shopping, give you email
in your kitchen or simply call for maintenance when needed. We
carry with us WAP phones and smartcards, have security systems that
monitor us and web cams that show our homes to the world. 1.
INTRODUCTION
The keyboard is still one of the most common input devices in
use today. Allows rapid entry of text by experienced users Usually
connected by cable, but can be wireless It is used for entering
textual data and commands. The vast majority of keyboards have a
standardized layout, and are known by the first six letters of the
top row of alphabetical keys, QWERTY. 1. TEXT ENTRY DEVICES :
keyboards
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The QWERTY keyboard: :1. TEXT ENTRY DEVICES: The alphanumeric
keyboard Standardised layout but non-alphanumeric keys are placed
differently accented symbols needed for different scripts minor
differences between UK and USA keyboards QWERTY arrangement not
optimal for typing layout to prevent typewriters jamming!
Alternative designs allow faster typing but large social base of
QWERTY typists produces reluctance to change.
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alphabetic keyboard : keys arranged in alphabetic order not
faster for trained typists not faster for beginners either! DVORAK:
common letters under dominant fingers biased towards right hand
common combinations of letters alternate between hands 10-15%
improvement in speed and reduction in fatigue 1. TEXT ENTRY
DEVICES: The alphanumeric keyboard:
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Only a few keys, four or five, are used and letters are
produced by pressing one or more of the keys at once. 1. TEXT ENTRY
DEVICES: The chord keyboard
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use numeric keys with multiple presses 2 a b c6 - m n o 3 - d e
f 7 - p q r s 4 - g h I 8 - t u v 5 - j k l 9 - w x y z hello =
4433555[pause]555666 surprisingly fast! 1. TEXT ENTRY DEVICES:
Phone pad and T9 entry:
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T9 predictive entry type as if single key for each letter use
dictionary to guess the right word hello = 43556 1. TEXT ENTRY
DEVICES: Phone pad and T9 entry:
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Text can be input into the computer, using a pen and a
digesting tablet natural interaction Technical problems: segmenting
joined up writing into individual letters interpreting individual
letters coping with different styles of handwriting Used in PDAs,
and tablet computers leave the keyboard on the desk! 1. TEXT ENTRY
DEVICES: Handwriting recognition:
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Improving rapidly Most successful when: single user initial
training and learns peculiarities limited vocabulary systems
Problems with external noise interfering imprecision of
pronunciation large vocabularies different speakers 1. TEXT ENTRY
DEVICES: Speech recognition:
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for entering numbers quickly: calculator, PC keyboard for
telephones. 1. TEXT ENTRY DEVICES: numeric keypads: 456 789 * 0#
123 456 123 0. = 789 TelephoneCalculator
2. POSITIONING, POINTING AND DRAWING : Central to most modern
computing systems is the ability to point at something on the
screen and manipulate it There has been a long history of such
devices, in particular in computer-aided design (CAD), where
positioning and drawing are the major activities. Pointing devices
allow the user to point, position and select items, either directly
or by manipulating a pointer on the screen.
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2. POSITIONING, POINTING AND DRAWING : Many pointing devices
can also be used for free-hand drawing although the skill of
drawing with a mouse is very different from using a pencil. The
mouse is still most common for desktop computers, but is facing
challenges as laptop and handheld computing increase their market
share.
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2. POSITIONING, POINTING AND DRAWING : The mouse Handheld
pointing device very common easy to use Two characteristics planar
movement buttons (usually from 1 to 3 buttons on top, used for
making a selection, indicating an option, or to initiate drawing
etc.)
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2. POSITIONING, POINTING AND DRAWING : The mouse How does it
work? Mechanical: Ball on underside of mouse turns as mouse is
moved Can be used on almost any flat surface Optical: light
emitting diode on underside of mouse may use special grid-like pad
or just on desk less susceptible to dust and dirt
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2. POSITIONING, POINTING AND DRAWING : The touchpad small touch
sensitive tablets stroke to move mouse pointer used mainly in
laptop computers good acceleration settings fast stroke lots of
pixels per inch moved initial movement to the target slow stroke
less pixels per inch for accurate positioning
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2. POSITIONING, POINTING AND DRAWING : Trackball and
thumbwheels Trackball : ball is rotated inside static housing like
an upsdie down mouse! relative motion moves cursor indirect device,
fairly accurate separate buttons for picking very fast for gaming
used in some portable and notebook computers. Thumbwheels : for
accurate CAD for fast scrolling
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2. POSITIONING, POINTING AND DRAWING : Joystick and keyboard
nipple Joystick : Indirect pressure of stick = velocity of movement
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
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2. POSITIONING, POINTING AND DRAWING : Touch-sensitive screen
Detect the presence of finger or stylus on the screen. works by
interrupting matrix of light beams, capacitance changes or
ultrasonic reflections direct pointing device Advantages: fast, and
requires no specialized pointer good for menu selection suitable
for use in hostile environment: clean and safe from damage.
Disadvantages: finger can mark screen imprecise (finger is a fairly
blunt instrument!) difficult to select small regions or perform
accurate drawing lifting arm can be tiring
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2. POSITIONING, POINTING AND DRAWING : Stylus and light pen
Stylus small pen-like pointer to draw directly on screen use touch
sensitive surface or magnetic detection used in PDA, tablets PCs
and drawing tables Light Pen now rarely used uses light from screen
to detect location BOTH very direct and obvious to use but can
obscure screen
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2. POSITIONING, POINTING AND DRAWING : Digitizing tablet
Digitizing tablets are used for freehand drawing. capable of high
resolution, and are available in a range of sizes. very accurate:
used for digitizing maps Problems with digitizing tablets are that
they require a large amount of desk space, and may be awkward to
use if displaced to one side by the keyboard.
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2. POSITIONING, POINTING AND DRAWING : Eyegaze allow you to
control the computer by simply looking at it! Some systems require
you to wear special glasses or a small head- mounted box, others
are built into the screen or sit as a small box below the screen It
is fine for selection but not for drawing. potential for hands-free
control uses laser beam reflected off retina very fast and accurate
device, but the more accurate versions can be expensive.
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2. POSITIONING, POINTING AND DRAWING : Cursor keys Four keys
(up, down, left, right) on keyboard. Very, very cheap, but slow.
Useful for not much more than basic motion for text-editing tasks.
No standardised layout, but inverted T, most common
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3. VIRTUAL REALITY AND 3D INTERACTION: Positioning in 3D space
Moving and grasping Seeing 3D (helmets and caves)
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3. VIRTUAL REALITY AND 3D INTERACTION: Positioning in 3D space
Cockpit and virtual controls steering wheels, knobs and dials just
like real! The 3D mouse six-degrees of movement: x, y, z + roll,
pitch, yaw 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
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3. VIRTUAL REALITY AND 3D INTERACTION: Positioning in 3D space
pitch, yaw and roll pitch yaw roll
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3. VIRTUAL REALITY AND 3D INTERACTION: 3D displays desktop VR:
ordinary screen, mouse or keyboard control perspective and motion
give 3D effect seeing in 3D: use stereoscopic (( vision VR helmets
screen plus shuttered specs, etc.
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3. VIRTUAL REALITY AND 3D INTERACTION: 3D displays VR headsets:
small TV screen for each eye slightly different angles 3D
effect
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4. PHYSICAL CONTROLS, SENSORS AND SPECIAL DEVICES : special
displays and gauges sound, touch, feel, smell physical controls
environmental and bio-sensing
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4. PHYSICAL CONTROLS, SENSORS AND SPECIAL DEVICES : Special
displays analogue representations: dials, gauges, lights, etc.
digital displays: small LCD screens, LED lights, etc. head-up
displays: found in aircraft cockpits show most important
controls
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4. PHYSICAL CONTROLS, SENSORS AND SPECIAL DEVICES : Sounds
beeps, bongs, clonks, whistles and whirrs used for error
indications confirmation of actions e.g. Keyclick
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4. PHYSICAL CONTROLS, SENSORS AND SPECIAL DEVICES : Touch, feel
and smell touch and feeling important: in games vibration, force
feedback in simulation feel of surgical instruments called haptic
devices texture, smell, taste: current technology very limited
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4. PHYSICAL CONTROLS, SENSORS AND SPECIAL DEVICES : Environment
and bio-sensing sensors all around us car courtesy light small
switch on door ultrasound detectors security, RFID security tags in
shops temperature, weight, location and even our own bodies iris
scanners, body temperature, heart rate, galvanic skin response,
blink rate
5. PAPER: PRINTING AND SCANNING Printing image is made from
small dots allows any character set or graphic to be printed,
critical features: resolution size and spacing of the dots measured
in dots per inch (dpi) speed usually measured in pages per
minute
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5. PAPER: PRINTING AND SCANNING Types of dot-based printers
dot-matrix printers : use inked ribbon (like a typewriter) line of
pins that can strike the ribbon, dotting the paper. typical
resolution 80-120 dpi ink-jet and bubble-jet printers : tiny blobs
of ink sent from print head to paper typically 300 dpi or better.
laser printer : like photocopier: dots of electrostatic charge
deposited on drum, which picks up toner (black powder form of ink)
rolled into paper which is then fixed with heat typically 600 dpi
or better.
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5. PAPER: PRINTING AND SCANNING Printing in the work space shop
tills : dot matrix may print cheques same print head used for
several paper rolls thermal printers : special heat-sensitive paper
paper heated by pins makes a dot used in some fax machines poor
quality, but simple & low maintenance
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5. PAPER: PRINTING AND SCANNING Fonts Font the particular style
of text Courier font Helvetica font Palatino font Times Roman font
(special symbol) Size of a font measured in points (1 pt about
1/72) (vaguely) related to its height This is twenty-four point
Harlow solid italic This is eighteen point This is twelve
point
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5. PAPER: PRINTING AND SCANNING Fonts Pitch fixed-pitch every
character has the same width e.g. Courier variable-pitched some
characters wider e.g. Times Roman Serif or Sans-serif sans-serif
square-ended strokes e.g. Helvetica serif with splayed ends (such
as) e.g. Times Roman or Palatino
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5. PAPER: PRINTING AND SCANNING Readability of text lowercase
easy to read shape of words UPPERCASE better for individual letters
and non-words e.g. flight numbers: BA793 vs. ba793 serif fonts
helps your eye on long lines of printed text but sans serif often
better on screen
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5. PAPER: PRINTING AND SCANNING Screen and page WYSIWYG what
you see is what you get aim of word processing, etc. but screen: 72
dpi, landscape image print: 600+ dpi, portrait can try to make them
similar but never quite the same so need different designs,
graphics etc, for screen and print
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5. PAPER: PRINTING AND SCANNING Scanners Printers take
electronic documents and put them on paper scanners reverse this
process. The image to be converted may be printed, but may also be
a photograph or hand-drawn picture. There are two main kinds of
scanner: hand-held: Flat-bed:
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5. PAPER: PRINTING AND SCANNING Scanners Scanners work by
shining a beam of light at the page and then recording the
intensity and color of the reflection. Like photocopiers, the color
of the light that is shone means that some colors may appear darker
than others on a monochrome scanner. Like printers, scanners differ
in resolution, commonly between 600 and 2400 dpi
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6. MEMORY: Like human memory, we can think of the computers
memory as operating at different levels, with those that have the
faster access typically having less capacity. By analogy with the
human memory, we can group these into short-term and long-term
memories (STM and LTM).
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6. MEMORY: RAM and short-term memory (STM) Most currently
active information is held in silicon-chip Random Access Memory
(RAM). Typical access times are of the order of 10 nanoseconds,
that is a hundred-millionth of a second. Information can be
accessed at a rate of around 100 Mbytes (million bytes) per second.
Typical storage in modern personal computers is between 64 and 256
Mbytes. Its contents are lost when the power is turned off.
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6. MEMORY: Disks and long-term memory (LTM) There are two main
kinds of technology used in disks: magnetic disks and optical
disks. Magnetic disks: The most common storage media, floppy disks
and hard (or fixed) disks, are coated with magnetic material, like
that found on an audio tape, on which the information is stored.
Optical disks: use laser light to read and (sometimes) write the
information on the disk. There are various high capacity specialist
optical devices, but the most common is the CD-ROM.