COMP 1017
Session 3: Input and Output
What is a peripheral?
Activity
• List of input devices
History 1: the Jacquard Loom
• Punched cards determine the pattern
woven
• Inputting information to the machine,
which then uses it to manufacture a
product
• Different cards for different products
Jacquard Loom (1804-5)
from http://history.acusd.edu/gen/recording/jacquard1.html
History 2: Punched cards
• Hollerith’s US census analysis (1890)
• Developed into sophisticated data input
• Cards punched and read using special
machines
• 80 columns per card
• Reading: up to 1000 cards per minute
• Punching: slow
Punched cards (continued)
• Variety of coding patterns
• Easy to get cards into wrong order
• Bulky (7 3/8 inches wide by 3 1/4 inches
high each)
Do not fold, spindle or mutilate
from http://freespace.virgin.net/tony.brown7/computer/
Punched Card Reader
from
http://www.nersc.gov/~deboni/Computer.history/MachineScans/CompHistMachineS
cans2/unknown.card.reader.jpg
History 3: Paper Tape
• Punched holes again
• Much harder to correct than cards
• But more compact (1 inch across)
Paper tape
from http://www.computersciencelab.com/ComputerHistory/History.htm
Contemporary inputs 1:
Keyboard
• Input alphanumeric characters
and others
• List of other characters?
how do you get them?
• Other functions of keys?
Keyboard layouts
• Standard: QWERTY layout
• Designed by Scholes to slow down
typists
mechanical typewriters couldn’t cope
with high typing speeds
• Not the most efficient for high speed
typing
Other key layouts designed
Keyboard
from http://www.iowaworkforce.org/wc/edi/edi.htm
Keyboard layouts
from http://www.webopedia.com/TERM/D/Dvorak_keyboard.html
Ergonomics
• the study of the relationship between
individuals and their work or working
environment
• Includes making a keyboard easy to use
Change tilt
Different sections for each hand, in
different orientations
RSI
• Repetitive Strain Injury (RSI)
Caused by repeated actions,
including typing and mouse-clicking
usually in non-ideal ergonomic
situations
• Wrist support also important for typists
• Special keyboards available for disabled
Ergonomic Keyboard
from http://www.e-pcs.co.uk/
Ergonomic Keyboard (2)
from http://www.barrybennett.co.uk/hardware/miceandkeyboards/goldtouch.htm
Datahand
from http://www.datahand.com/overview/photos.htm
Bad keyboards
• Too small (ZX-80, PDAs)
need stick to push keys
very slow input
• Not adjustable (laptops, PDAs)
uncomfortable to use
Special function keyboards
• Each key has special function
• e.g. McDonalds tills
Cash machines (hole in the wall)
Combination locks
Alarm systems
Cashpoint
from http://news.bbc.co.uk/1/hi/business/1190181.stm
GUI (Graphical User Interface)
• Original interfaces (e.g. DOS, Unix,
Linux): command-based
commands typed in using keyboard
• GUI: icons on screen to initiate actions
• Non-text interaction possible
Particularly pointing
DOS command window
Inputs 2: Pointing
• Move cursor to desired location on
screen, and initiate action
• Cursor movement by up/down/left/right
keys (text interface)
• Or by mouse (graphical interface)
• Action initiated by pressing ‘Enter’
or clicking the appropriate mouse
button
Mouse
from http://www.lscc.edu/learningcenters/links.asp
Another computer mouse
from http://www.thejokefactory.org/JF_pictures/computer/Computer_index.htm
How a mouse works
• Roller ball underneath
• Motion of mouse causes ball to roll
• Ball contacts two rollers in
perpendicular directions
• Motion of rollers sensed and used to
move cursor on screen
• (Third spring-loaded roller to keep ball
in position)
Inside a computer mouse
from http://www.seanet.com/~harrypy/MorseMail/PCMouse.html
Further inside…
from http://www.seanet.com/~harrypy/MorseMail/PCMouse.html
Problems with mice
•
•
•
•
Ball rollers get dirty – need cleaning
Need good surface – mouse mat
Always running off the edge of the mat
How fast do you have to double-click?
Advanced mice
• Optical technology
does away with moving parts
works on most surfaces
• Infra-red mouse - cordless
Mouse alternatives
• Track(er)ball – mouse with ball on top
Or ball embedded in the keyboard
popular with laptop makers
(but not always with users)
• Trackpoint
miniature joystick between G, H and B
on keyboard
Trackball mouse
from http://www.oucs.ox.ac.uk/enable/index.xml?style=printable
Trackpoint
from http://www.laptopworldwide.com/ri/howlaptopswork/fact2.htm
More mouse alternatives
• Touch sensitive screens
Use pen (or finger) as pointing device
popular in PDAs (Personal Digital
Assistants)
Types: pressure-sensitive
capacitive surface
light beam
Another mouse alternative
• Touchpad
Position-sensitive pad
Found in many laptops
motion of finger on pad analysed and
used to move cursor
Touchpad
from http://www.ks.uiuc.edu/~kvandivo/laptop/
• Good and bad things about different
types of pointing device
mouse
trackball
trackpoint
touch-sensitive screens
touchpads
WIMPs
• Nuclear physics:
– Weakly Interacting Massive Particle
• Sociology:
– Weak Incompetent Meandering Pussy
• Computer user interfaces:
Windows
Icons
Menus
Mouse
Pointer
Pull-down menu
Inputs 3: Scanners
• Read in from sheet of paper
flat bed: moving sensor past paper
sheet feed: moving paper past
sensor
hand held: moving sensor in hand
Flatbed Scanner
from http://www.obmlink.com/product/op9636t.html
• Which type of scanner is best?
• Why?
Inputs 4:
Automated Data Capture
• Manual methods are:
labour-intensive
expensive
error-prone
Barcode scanners
• Used in supermarkets
• Need to be able to scan
forwards
backwards
in any orientation
• System can include automatic stock
record updates
Barcode scanner – library
from http://www.ysgolrhiwabon.co.uk/images/librarypix/dans_tour/barcodescanner.jpg
Barcode scanner – hospital
from http://www.cryo-imt.com/images/Barcode%20Scanner.jpg
Inputs 5: Graphics tablets
• Touch-sensitive screen
• Responds to position and force
• Used for inputting free-hand graphics
Graphics tablet
from http://www.sonic.net/~ideas/art_mma5.html
Other inputs (1)
• Magnetic Ink Character Recognition
(MICR)
used on cheques for sorting
• Optical Mark Recognition (OMR)
reads pencil marks
e.g. m/c test answer sheets
Other inputs (2)
• Optical Character Recognition (OCR)
recognises alphanumeric characters
e.g. postcodes
• Video
digital cameras – via memory cardse
web cams
video conferencing
Other inputs (3)
• Audio input
Microphone
MIDI (Musical Instrument Digital
Interface)
• Speech recognition
machine needs to be trained to
recognise a particular voice
Other inputs (4)
• Movement input
Joystick (games)
Virtual reality sensors
• Data input
scientific measurements
process control
e.g. coffee maker
Output Devices
• Where does the output go?
Output Destinations
•
•
•
•
•
People
Other computers
Environment
Robots
Central heating
How does output get to
people?
Outputs to people
• Vision
graphics card + VDU
(printer is a type of computer)
• Sound
sound card + speakers
• Touch
haptic feedback
• Others: smell, taste, thought?
Outputs 1: Visual
Cathode Ray Tube (CRT)
from http://www.probertencyclopaedia.com/SC.HTM
Raster scanning
from http://web.onetel.net.uk/~uncletony/tv-stuff.htm
Converting numbers to
voltage
Numbers in
Voltage out
6788854111
D to A
1344514223
2333345677
Digital data
Digital to Analogue
conversion
Analogue data
Colour CRT
from http://www.ul.ie/~idc/hci/lecture07/lecture07.html
Memory
• How much data needed for one pixel?
• How much data needed for one
complete screen (800 x 600 pixels)?
• Screen is refreshed 25 time per second.
How much data sent to screen per
second?
Graphics processor
•
•
•
•
Handles large amounts of data
Draws lines
Fills in areas of colour
Renders textures
Lines
from http://zobal.free.fr/tuts/drag/en_drag3.htm
Textured
from http://zobal.free.fr/tuts/drag/en_drag3.htm
Image restoration
from http://www.cs.uoi.gr/~galatsanos/IMAGE%20RESTORATION.htm
Image restored
from http://www.cs.uoi.gr/~galatsanos/IMAGE%20RESTORATION.htm
LCDs (Liquid Crystal Displays)
•
•
•
•
•
2 polarising filters with liquid crystal between
Filters right angles to each other
Crystal rotates plane of polarisation by 90º
Normally, light gets through
Apply voltage to parts of crystal
rotates direction of polarisation by 90º
• Light does not get through in those parts
LCD
from http://www.vcalc.net/display2.htm
Plasma screens
•
•
•
•
Array of tiny fluorescent lights
Individually controlled
RGB filters to give colour
Larger viewing angle than LCD displays
Plasma Screen
from http://freeplasmatv.halyava.net/
Outputs 2: Printers
Types of Printer
• Impact printers:
Typewriter
Dot matrix
• Ink jet
• Laser
Inkjet printers
• Ink forced out of small nozzle in spurts
• Spots of ink on paper build up
characters or image
• Poor quality paper gives burred dots
Laser printers
• Drum positively charged
• Selectively negatively charged by laser
• Positively charged toner sticks only to
negative parts
• Toner transferred to paper and fixed to
paper by heating
• Drum completely discharged for next
cycle
Laser Printer
from http://www.jc-computers.org/Printers.htm
No charge
positive
Laser Printer
negative
2. Drum gets pos charge
3. Laser writes ‘A’, makes
drum negative there.
laser
1. Uncharged drum
A
8. Drum discharged
Positive toner
4. Pos toner sticks to neg ‘A’
A
A
A
5. Paper charged neg
6. Neg paper
attracts pos ‘A’
A
7. Paper discharged
Electronic paper
from http://www.signonsandiego.com/news/computing/200305070607-technology-e-paper.html
Electronic ink
from http://www.spectrum.ieee.org/publicfeature/oct00/dispf5.html
Outputs 3:
Holographic projection
from http://fantasyscifi.topcities.com/startrek/voyager/doctor/doctor.html
Outputs 4: Haptic feedback/VR
from http://www.dcs.ed.ac.uk/teaching/cs4/www/graphics/Web/intro_graphics/vr.htm
Haptic Feedback in Remote
Robotics
1. User moves hand
6.
… user feels force
2. Position info sent …
Sends force info
5.
3.
… to remote robot
4. Robot responds
From http://www.dvirc.org.au/whenlove/friends.htm