NSS-ICT‎ > ‎Unit B‎ > ‎

Chapter 12

Input and Output Devices

12.1 Input Devices
Keyboards, MIDI keyboard, ergonomics keyboard
Pointing devices: used for GUI, 
  example: mouse(mice), Trackballs, touch pads, track Points, Joysticks, Touch screens,
               Digitizing tablets, handwriting boards
Image scanner: 
used with optical character recognition (OCR) software to convert image to text.
 Major specexamples 
 Type Flatbed
 Scanning mode grey scale: 16 bits per pixel
 Color:  48 bits per pixel
 Dimension A4, F4, A3 
 Resolution 2400 dpi x 2400 dpi 
 Interface  USB 2.0 

Optical reader:
Bar code readers: fast and more accurate than keyboard input.
Optical Mark readers: MC answer sheets, questionnaire, forms

Used with speech recognition software

Digital cameras and Digital video cameras, Web cam
Major spec: DC
 Resolution 1920x1080 = 2M pixels 
 Additional features Wi-Fi connections, GPS ... 


12.2 Output devices
Visual Display Unit: Cathode Ray Tube, Liquid Crystal display, LED display (Some are Lighting only)

Comparing the Physical size and Energy consumption of LCD, LED and CRT display.

Some major specification of LCD, LED.
 Specification Details
 Size of Display e.g. 22", 24" 
 Resolution e.g. 1920 x 1080 (HDMI)
 Contrast, response time Important for playing games, not important for using word processor.
 Viewing Angle Large the better ?? 
 Power Consumption Energy Saving 
 Interface e.g.  VGA, DVI, HDMI (including sound) 
 Additional feature USB hubs, Speaker 

Speakers/ Headphone (stereo, mono)

 Types Major advantages 
 Dot matrix (impact) Produce carbon copy
 print continuous form 
 Inkjet printers High quality 
 Laser printers High quality with lower running cost than Inkjet 
 Thermal printers No need to refill ink, toners.
 Thermal paper is needed. 
 Very quite, without moving parts

Page printer: e.g. laser printer: Memory size (Cache size) is important.
Speed: ppm (Page per print)
resolution: e.g. 600 dpi

3D printers
Multi-function printers: Scanning, copying, fax etc.

Video projectors

12.3 Daily applications of input and output devices (Exam coverage will not be confined to the example below)

Identify the input and output devices of a POS terminal, cheque deposit machine, cash deposit machine, iCenter at MTR (P.58), Kiosk at Shopping Mall etc.
SOHO (Small office and Home office) 
Telecommuting: Work outside office using IT. 
Multi-function printer: Scanner, printer, fax, photocopier.
Conference Room

3_ICT 2016--Input Devices