Learning About Parts of
Computer
ADE100- Computer Literacy
Lecture 02
Knowledge test
• What is computer?
• Briefly explain role of Charles Babbage.
• What is the purpose of input devices?
• What is the role of Joystick & OCR?
Topics covered
• Input devices (contd.)
• Interfacing with the computer using mouse &
keyboard
• Output devices
• Storage devices
• Understanding of Central Processing Unit (CPU)
• How do computers work?
What is input?
• Any data or instructions used by a computer
• Types of input:
• Data- text form
• Instructions- particular commands
• Voice- audio signals through microphone
• Image- inserting a picture
The Keyboard
• How keyboard works?
• Keyboard controller (a tiny chip) detects a key
pressed and places a code into its memory called
buffer (a temporary memory area).
• Controller sends a code to the CPU
• Code represents the key pressed
• Controller sends a signal to the operating system
• Operating system responds
• Controller repeats the letter if held
The Mouse
• Common mouse actions are:
• Right click
• Left click
• Drag & drop
• Move
• Scroll
• Double click
The Mouse
• Benefits
• Pointer positioning is fast
• Menu interaction is easy
• Users can draw electronically
The Mouse
• Mouse button
configuration
• Configured for a righthanded user
• Can be reconfigured
• Left mouse button is
called a primary button
• Extra buttons are
configurable
• Procedure
• Go to control panel
• Double click mouse icon
Ergonomics and Input Devices
• Ergonomics
• Study of human and tool interaction
• Concerned with physical interaction
• Attempts to improve safety and comfort
Ergonomics and Input Devices
• Repetitive Strain/Stress Injury (RSI)
• Caused by continuous misuse of the body
• Many professionals suffer from RSI
• Carpal Tunnel Syndrome (CTS)
• Carpal tunnel is a passage in the wrist
• Holds nerves and tendons
• Prolonged keyboarding swells tendons
Carpal Tunnel Syndrome
11
Ergonomics and Input Devices
• Office hardware suggestions
• Office chairs should have
• Adjustable armrests and height
• Armrests
• Lower back support
• Desks should have
• Have a keyboard tray
• Keep hands at keyboard height
• Place the monitor at eye level
Ergonomics and Input Devices
• Techniques to avoid
RSI
• Sit up straight
• Have a padded wrist
support
• Keep your arms straight
• Keyboard properly
• Take frequent breaks
What is output?
• Processed data or information
• Types of output
• Text
• Graphics like charts, graphs, pictures
• Audio & video
• Output devices
• Monitors
• Printers
• Speakers
• Projectors
Monitors
• Known as screens or display screens
• Output referred to as soft copy
• Categorized by color output
• Monochrome
• One color with black background
• Grayscale
• Varying degrees of gray
• Color
• Display 4 to 16 million colors
Measuring quality of monitors
• Resolution
• Refers to sharpness & clearness of image
• More no. of pixels means high resolution
• E.g. 800x600 means 800 horizontal, 600 vertical
• Dot pitch
• Distance between each pixel on screen
• It also determines picture clarity
• Smaller distance b/w pixels shows higher sharpness
of image
Measuring quality of monitors
• Refresh rate
• No. of times per second the electron gun scan
every pixel on the screen
• Measured in Hertz (Hz) or Cycles per second
• Pixels fade after some time so need to refresh
• Normally 75 times per second
• Size
• Measured diagonally in inches
• Distance from corner to corner
• Different sizes like 14, 15, 17, 21, 22 inches.
Types of monitors
• Cathode-ray tube monitors or CRTs
• Flat-panel
• Liquid crystal display (LCD)
• Portable and thinner than CRTs
• Other monitors
• E-books
• Data projectors
• High-definition television (HDTV)
Printers
• Translates information that has been processed
by the system unit
• Output referred to as hard copy
• Features
• Resolution
• Color capability
• Speed
• Memory
More on printers
• Ink-jet printer
• Use ink/cartridge
• Both black & color
• Laser printer
• Personal laser printers
• Shared laser printers
• Other printers
• Dot-matrix
• Plotters
• Photo printers
Audio output devices
• Translates audio information into sounds that
people can understand
• Sound card
• Between CPU & speakers
• Converts digital signals to analog
• Common devices
• Speakers
• Headphones
Data projectors
• Project image onto wall or screen
• LCD projectors
• Most common type of projector
• Small LCD screen
• Very bright light
• Require a darkened room
• Digital Light Projectors
• A series of mirrors control the display
• May be used in a lighted room
Combined I/O devices
• Fax machines
• Multifunction devices
• Digital camera
• Internet telephones
• Terminals
• Keyboard and monitor
Storage devices
• Store data when computer is ON/OFF
• Two processes
• Writing data
• Reading data
• Primary storage devices
• RAM & ROM
• Permanent storage devices
• Magnetic storage devices
• Optical storage devices
• Mobile storage devices
Primary storage
• RAM
• Random Access Memory
• Stores open programs and data
• Small chips on the motherboard
• More memory makes a computer faster
• 512MB, 1GB up to 4GB
• ROM
• Read Only Memory
• ROM-BIOS
Computer RAM
and CPU
- Right click My Computer
- Select properties from
menu
26
Secondary storage devices
• Stores data when computer is OFF
• Three types
• Magnetic storage devices
• Hard disk drives, floppy disks,
• Optical storage devices
• CD, DVD
• Mobile storage devices
• Online storage
• Flash memory
• Memory cards
Magnetic storage
• Data organization
• Disks must be formatted before use
• Format draws tracks on the disk
• Tracks is divided into sectors
• Amount of data a drive can read
Magnetic storage
• Hard disk drive
• Secondary storage device in a computer
• 2 or more aluminum platters
• Each platter has 2 sides
• Spin between 5,400 to 15,000 RPM
• Data found in 9.5ms or less
• Drive capacity greater than 40 GB
30
Optical storage devices
• CD-ROM (Compact Disk Read Only Memory)
• Read using a laser
• Lands, binary 1, reflect data
• Pits, binary 0, scatter data
• CD speed is based on the
• Original CD read 150 Kbps
• A 10 X will read 1,500 Kbps
• Standard CD holds 650 MB
• CD-R (Compact Disk Recordable)
• Write data once
• CD-R/W (Compact Disk Rewriteable)
• Write data multi times
• Combo drive (CD R/W, DVD-R)
Optical storage
• DVD- (Digital Versatile Disk)
• Digital Video Disk
• Use both sides of the disk
• Capacities can reach 18 GB
• DVD players can read CDs
• DVD-R
• DVD recordable once
• DVD-R/W
• DVD Rewriteable multi times
• Super drive- (CD R/W +DVD R/W)
Mobile storage devices
• Online storage
• Dropbox, Google drive
• Flash memory
• Found in cameras and USB drives
• Combination of RAM and ROM
• Long term updateable storage
• Smart cards
•
•
•
•
Credit cards with a chip
Chip stores data
Eventually may be used for cash
Hotels use for electronic keys
CPU- Central Processing Unit
• The CPU
• Brain of the computer
• Components of CPU
• Control unit
• Controls resources in computer
• Acts like Traffic Policeman
• Arithmetic logic unit
• Simple math operations
• Registers
Working of CPU
• Machine cycles
• Steps by CPU to process data
• Instruction cycle
• CPU gets the instruction
• Execution cycle
• CPU performs the instruction
• Billions of cycles per second
• Multitasking allows multiple instructions
Information Processing Cycle
• Four steps followed to process data
• Input
• Processing
• Output
• Storage
Activity-20 minutes
• Practice the use of mouse by selecting different icons
on your desktop or in My computer.
• Briefly talk about different parts of a real keyboard.
• Detach and attach different input and output devices
of your computer.
• Install a typing tutor on your computer from a
CD/DVD/internet.
• Practice first lesson for 15 minutes.
Further reading
• “Introduction to Computers” by Peter Norton,
7th edition.
• 1B- Looking inside the computer system
• 2A- using the keyboard & mouse
• 3A- Video & sound
• 3B- Printing
• 4A- Transforming data into information
• 5A- types of storage devices
Thanks
End of Lecture 02
39
Allah Hafiz
40