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Using Information Technology Chapter 5 Hardware: Outside the box Expected outcome after this lecture After this lecture, students are expected to be able to: Give examples on different types of Input and Output devices Understand how mechanical and optical mouse works

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Using Information Technology

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using information technology

Using Information Technology

Chapter 5

Hardware: Outside the box

expected outcome after this lecture
Expected outcome after this lecture

After this lecture, students are expected to be able to:

  • Give examples on different types of Input and Output devices
  • Understand how mechanical and optical mouse works
  • Discuss the advantages and features provided by different types of scanners (handheld v.s. flatbed)
  • Explain how CRT monitor and LCD monitor works and compare their relative advantages
  • Perform simple calculation on display memory
  • Explain the different attributes of a monitor (resolution, color depth, dot pitch, refresh rate…)
  • Compare the mechanism and advantages of different types of printers
input device
Input device
  • Device that translate human readable data into data which can be understand and process by computer
  • 3 types:
    • Keyboard type devices – converts characters into computer readable form
    • Pointing devices – control the position of cursor or pointer on the screen
    • Source data-entry devices – converts other form of data into computer readable form
how to get input from keyboard
How to get input from keyboard?
  • When a key is pressed, the scan code is generated and the character will be stored in buffer for further process.
  • Information is sent to PC via PS/2 or USB port
  • Wireless interface is becoming more common
different types of keyboards
Different types of keyboards

101 Keyboard

- Total 101 keys

104 Keyboard (for Win)

- With Start Menu/Menu keys

Ergonomic Keyboards

-Reduce fatigue

the future
The future…

Virtual Laser



Virtual Keyboard

mechanical mouse
Mechanical Mouse

Use a rubber ball to detect motion

Inside the socket, there are 2 rollers

arranged at 90o

A Roller moves a wheel with holes

The wheel block/unblock the light of

Infrared LED emitter/receiver, hence

enable the detection of speed

optical mouse
Optical Mouse
  • No ball / wheel
  • Work on almost all surfaces
  • LED at the bottom emits light to surface
  • Light rebound and is captured by sensor
  • (Taking 1500 pictures per second)
  • Pictures are sent to Digital Signal Processor (DSP) to detect the motion
multi touch
  • Multi-touch technology is becoming more and more common nowadays
  • Apart from specifying position(s) as in typical pointing devices and touch-screen, multi-touch supports “Gestures” which is mapped to operations like zoom, reload, flip page…etc
in the news microsoft surface
In the News: Microsoft-Surface
  • Computer from MS, supporting multi-touch gesture, multi-user interaction and object recognition.
  • Possibilities:
    • Project/Games with multi-users
    • Information counters (e.g. showing maps, menus..etc)
    • Art / Entertainment (draw picture with a “real” brush?)
    • Interaction with other hand-held devices…etc.
source data entry devices
Source data-entry devices
  • No keystroke is required to input data
  • Data is entered directly from the source and translated into digital format
    • Bar-code reader
    • Digital camera
    • Fax machine
    • Image scanner
    • Voice recognition
    • Biometric scanner (e.g. fingerprint)
  • Handheld scanner
    • Rely on the user to move
    • Poor image quality
  • Flatbed scanner
    • Light and sensor moved by motorized belt.
  • Additional Features
    • Scanning of photographic negatives
    • Auto Document Feeder
    • Software: Denoise, OCR (Optical Character Recognition)
output device
Output device
  • Device that translate information processed by computer into human readable form
  • Two Types:
    • Hardcopy
      • In a printed form
      • Printer, plotter, microfilm, microfiche
output devices
Output devices
  • Softcopy
    • Display on screen, voice output, sound output, video output, mechanical output
display screens
Display screens
  • Monitor, Cathode-Ray Tube (CRT)
    • A vacuum tube (chamber) used as a display screen
    • The screen of a CRT is filled with Red/Green/Blue phosphor dots / pixels (picture element)
    • A CRT works by moving an electron beam back and forth across the back of the screen
    • When the beam pass across the screen, it lights up phosphor dots
    • Fast response time
    • Images are clear and bright
    • Big, heavy and consume more power
LCD – liquid crystal display
    • Light shine through a layer of crystalline liquid to make an image
    • Relatively Thinner and lighter
    • Low power consumption (only 1/3 of CRT)
    • Images might not be clearly viewed from an angle
    • Usually has longer response time and yields “motion blur”
how fine your display can be
How fine your display can be?
  • Screen size (diagonal length measured in inch)
  • Resolution
    • A measure of the number of pixels used for the whole screen
    • Determines the fineness of display details
    • 640480, 800600, 1024768, etc.
  • Color depth
    • Number of possible colors for each pixel
    • 256 color (8 bits), High color (16 bits), True color (24 bits)
calculation on the number of pixels
Calculation on the number of pixels
  • For 1280x1024 display, total number of pixels= 1280x1024 = 1310720 pixels = 1.3 Mega pixels
  • Assume the display uses True Color (24 bits)
  • Each pixel consumes: 24bits = 24/8 = 3 bytes
  • Total display memory = 1310720 x 3 = 4MB memory
Dot pitch
    • Amount of space between the centers of adjacent pixels
    • Smaller space  closer pixels finer image
  • Refresh rate
    • Number of times per second that the screen get refreshed
    • Pixels are recharged to remains bright
    • Higher refresh rate  More solid image
    • 60 Hz (1 second refresh 60 times)
the future22
The future…
  • 3D LCD monitor by Toshiba
  • Impact printer / Dot-matrix printer
    • Direct physical contact between printing mechanism and paper
    • Similar to a mechanical typewriter
    • 9 (low quality), 18 or 24 pins (best quality)
    • Noisy and slow
    • Still used nowadays to create “carbon copy” in Multi-Layered forms.
non impact printer
Non-impact printer
  • Without direct physical contact
  • Faster and quieter than impact printer
  • Ink-jet printers
  • Print head contains nozzles that are used to spray drops of ink
    • Heat (Bubble Jet by Canon, HP) vs Vibration (Epson)
  • 4 (common) or 6 colors
    • 4 colors – CMYK: Cyan, Magenta, Yellow, Black
    • 6 colors – CcMmYK: Cyan, cyan, Magenta, magenta, Yellow, Black
laser printer
Laser printer
  • Better quality and more expensive
  • Fire a laser beam on paper?
  • An electrostatic process (static electricity)
  • Black color or 4 colors (CMYK)
  • Fast printing speed (up to 35 ppm)
  • May be slower for color (8 ppm)
printer qualities
Printer qualities
  • Color
  • Resolution
    • The sharpness of text and images on paper
    • Measured in dots per inch (dpi)
    • Dot Matrix = 72-144, Ink Jet = 300-2400, Laser = 600-2400
  • Speed
    • Measured in characters per second (cps) or pages per minute (ppm)
  • Memory
    • A buffer holding the information waiting to be printed
    • More memory faster printing (8-32MB, up to 416MB)
comparison on color laser v s ink jet
Comparison on color laser v.s. ink jet
  • Problems of color ink jet:
    • Need high quality paper to prevent ink from feathering
    • Picture is less precise than color laser
    • Slow (high quality printing in ink jet may takes 10 mins)
    • Need to wait for a freshly printed page to dry
    • Ink-jet cartridges are more expensive than laser toner (Although the printer itself is cheaper)
all in one printer scanner fax
All-in-one Printer/Scanner/Fax
  • Nowadays, some printer firms (e.g. Hewlett-Packard) manufactures various models of all-in-one machines, which combines the functions of scanner, printer and modem
  • Scanner + Printer = Photo-copier
  • Scanner + Modem = Fax transmitter
  • Modem + Printer = Fax receiver
  • “Using Information Technology”, Ch 6